During 2-day hospital stay mom started having scary hallucinations that have not stopped (ex. devil, murder, blood, scary people). Advice?

See website: https://seniorservicesofamerica.com/blog/how-to-deal-with-hallucinations-in-the-elderly/

In part, it says:

How Do You Treat Hallucinations in the Elderly?

Hallucinations can be scary but they are not untreatable. Hallucinations are typically symptoms, not illnesses. Before you can treat hallucinations, you have to first determine the root cause. Once that is done, treatment can begin. 
If the patient is hallucinating due to Charles Bonnet Syndrome, lightening the environment might alleviate the hallucinations. If they are due to severe dehydration, once the patient is well again, finding a way to ensure they get enough water might remove the issue. 

If the root of the problem cannot be found, a doctor may prescribe an anti-anxiety med or an anti-depressant to help the patient relax and get more rest. 
Hallucinations can be treated in ways that often reduce or eliminate them so you should always seek medical care and find out what options are available. Never assume that hallucinations are par for the course with whatever a condition may be.

5 Ways to Respond to Your Loved One’s Hallucinations

Responding well is important when your loved one experiences a hallucination.

#1: Remove Possible Triggers From the Environment

Hallucinations are not always all in the head. Sometimes there are environmental triggers to consider. 

Sounds can be hallucination triggers. Do what you can to reduce or eliminate easily mistakable sounds such as the TV or an air conditioner. 
Nighttime hallucinations in elderly people are common and this can often be linked to shadows. 

Shadows can easily confuse someone prone to hallucinations so try and reduce them. Look around and see if there are shadows that look like something specific and do what you can to move objects around to eliminate the shadow.

#2: Stay Calm and Don’t Be Contradictory

Telling a loved one that what they are experiencing isn’t real might seem like the easiest and kindest reaction to a hallucination, but you should not do this. 
Especially if the hallucination is linked to dementia, someone experiencing this type of event is not able to rationalize that what they are seeing or experiencing is not real. 

Remain calm and collected and do not attempt to use logic or reason to convince them that they are hallucinating.

#3: Provide Reassurance and Validate Their Feelings

While you are staying calm, provide reassurance to the person experiencing the hallucination. Let them know that you are there to support them. 
If they seem to be gaining joy from the hallucination, you might try saying something like “I see that you are happy! I am so glad that what you are experiencing is bringing you joy!”

If their hallucination is frightening, you might respond with something like “I can see that you are scared. I am sorry that you are experiencing something so scary. I am here for you. How can I help you feel safe?” 

If they seem confused or disoriented, you might respond with “I can tell that you feel confused. How can I best help you?” 

Simply being present with your loved one through the hallucination can go a long way in helping them cope.

#4: Distract and Redirect

Distraction and redirection are powerful tools that you can use to help someone experiencing a hallucination. Do your best to take their attention off of the hallucination by directing them to something they enjoy. 
For instance, you could suggest:
Going for a walk
Doing a puzzle
Having a snack
Doing a chore or other task that makes them feel successful
Looking through old family albums

Sing their favorite song (if they are religious, a song from church might be helpful)

You can also try taking their attention off of the hallucination and placing it on you. For instance: If they are hearing voices — talk to them. It will be harder to make out those voices if they are listening to yours.  If they see something — make eye contact. Help them to look you in the eyes.

Gena / Touch Matters

When her ammonia level is elevated, she will have hallucinations. When her ammonia level is normal, she should not have this issue.

momtomymom: In conjunction with your mother's dementia, she may have suffered from hospital delirium.

My mother started doing that. She was seeing men outside her window and hearing alarms going off, etc. When she was taken to the hospital because the Home Health nurse could not get in the front door, they had to break down a window to get in. She was totally confused and disoriented. The hospital said she had a TIA and it affected her brain. Since then she has never been the same.

knowing that she is in kidney failure/ on dialysis, makes me wonder if it is a matter of her electrolytes being out of whack. I have seen patients with elevated ammonia levels show same symptoms as a schizophrenic. (I am/ have been a psychiatric RN for 30+yrs)

I would definitely talk with her doctor about this! It sounds like an important symptom or side effect. The doctor should be able to answer and possibly make some changes in the course of treatment!

Has she been taking the lactulose as many times a day as prescribed? I know that it is not pleasant to have several bowel movements a day, but that is how the body gets rid of the ammonia. I know that dialysis labs are routinely taken, but the probably are not checking an ammonia level. It would be a good idea to call her PCP about this.

End stage cirrhosis is famous for encepahlopathy. My husband (rest his soul) was given lactulose during pallative care. He scared me during his last weeks and thought that my eyes had changed colors that reflected cat eyes. I was putting on my makeup at the time he said this to me. It scared him and scared me too. My eyes are dark brown so I was wondering, what the heck was he seeing. It never dawned on me that it was the beginning stages of the hallucinations caused by the buildup of toxins in the blood.

How long has she been home?
Hospital induced delirium is a real thing, and usually disappears once back in normal environment for a week or so.
However, it is also real for a severe illness and major body system breakdown to usher in the beginnings of dementia.

This is something you need to discuss with the doctor at once.
Your mom's own case is as individual as her thumbprint, and only her own medical team and you yourself have enough knowledge of her particular case to make the best guesses. For a while guesswork is what you have, but if this is ongoing then there must be neuro-psyc testing.
Bodily functions, the back and forth of electrolyte balances, can work havoc on the brain. But once she is medically stable in own environment, this being still ongoing, there is something other afoot.

Every patient is a mystery. I spent my life as a nurse, but considered myself more a "detective". That's your job now. I wish you luck and hope you'll update us.
I don't know if you have ever undergone trauma, sometimes even good trauma as in childbirth, and afterward had a lot of violent and disturbing dreams. For some seniors the mind is already in such a weakened condition that some of these nightmare like things translate even to waking hours. I would give this a bit more time, but not much more before followup, and definitely speak with doc.

It could be related to medication. Not sure how old your mom is but older peoples' reactions to the same medications they've always taken changes. It happened to my MIL, my mom, and my husband. Once my MIL was discharged from the hospital it cleared up. I believe it may have been a narcotic medication she was given after a fall. We also took away Ambien from her once we read the side effects and in bold lettering it said "Not recommended for the elderly". Ambien is what was causing her to stagger and fall. My mom went through years of hospitalizations due to Crohn's disease and we quickly discovered one particular medication (Dilaudid) that caused her to hallucinate and affected her memory. For my husband it was morphine and the muscle relaxer, Soma, after back surgery that caused him to have evil dreams and hallucinations. These examples may have nothing to do with why your mom is having those dreams but I'd start with looking up the side effects of her medications.

Check for medication interactions with EVERYTHING (aspirin, supplements, cold medicine!!) else she takes, and read the medication documentation thoroughly. Lots of things can interact and cause wacky effects.

The first time my mom went into the hospital with me as her caregiver, she had had a couple minor strokes..... she had very vivid and "real" (to her) stories. At first I believed her. She said the night nurses were having parties in her room and in the hallways. When she went into rehab after the hospital for two weeks, she swore little kids were coming in her room and stealing her toothbrush!.. She has had 2 more hospital stays and every time she has vivid stories.... I have learned to just go along with her but hospital delirium is very real especially with vision and hearing impaired elders....

This is now a medical problem of diagnosis.
This could be anything from UTI to dementia to alcoholic encepalopathy to --as Joann says, hospital delirium or hepatic issues as you say.
We would only be guessing. THere is no comfort but medication at this point. I forget if this is a hospice case, but medication is the only answer and that will be dicey with a failing liver that cannot process things.

There is something callled Hospital delirium. If she has cirrhosis of the liver, the toxins given off can cause this problem too. You need to talk to her PCP.