After four years of caring for my mother she passed away. I left my work, friends and home to move to care for her. What now?

This is, indeed, caregiving. It's just the tail end of it, and everyone has to deal with it at some point.

I'm so sorry to hear of your mom's passing. It's bad enough to deal with the death of a loved one - especially a parent - but then to have to deal with all the "afters"...it's just insult added to injury.

Take your time and deal with it as need be. Don't rush unless there's some reason you have to.

There are many auction companies that will take the entire estate and sell it for you, and of course, they take a percentage for themselves, but it sounds like you don't want to deal with it on your own, so this may be a good option for you. I would start there - see if there's an estate auction company that will pick up the items and hold the auction online or elsewhere. Tell them having it at the property is not an option. Where I live, we have a local company that does both - they do on-site estate auctions, or they come and pick up everything not nailed down (literally, light fixtures and all, if that's what you tell them to do) and sell it online on their own website. It's a growing business model and works pretty well - they store the items at their warehouse, sell them online and the items are picked up at the warehouse by the buyers - the seller never need be involved other than being there when the company picks the items up from the house and then to receive their check for the sale later.

Unfortunately, these days unless an item is rare or a collector piece - things aren't worth as much as one would think. Even antiques- unless rare - can be difficult to sell with the owner or estate getting pennies on the dollar.

A neighbor of mine had an estate sale where they had a grandfathers clock that I looked up to find it cost $15,000 at time of original sale. The price at the estate sale was $300 and it was in pristine condition. The temptation was nearly overwhelming for me but practicality won out as I had no where to put it. In the end, it did not sell.

Sometimes it comes down to how much hassle you're willing to go through in deciding to try to sell estate pieces.

In my parents situation almost everything not selected by family was donated for the tax write-off. But yes, there are plenty of companies out there willing to help sell your things but they typically take a giant percentage of the money made - and they almost always hold the sale in the home as they have no showrooms.

It might be a good idea for you to take a little bit of time and look at eBay for comparable items to see what they're selling for. 

I'm sorry for the passing of your mom and that you are having to deal with this. I agree with giving yourself a bit of time. Sometimes we get rid of things only to miss them dearly a few weeks later. Take photos or a video.
Look for consignment shops but watch out for those too. They generally take about 40 to 50% of proceeds. Good ones will not want things that they don't think will move. Show them your photos or have them come to your home if you know them well enough.
Also depending on where you live, good auction houses are a quick way to move items. Many place their offerings online and folks buy online and at live auction at the same time. You could look on line for the sites. This is good for items like the clock mentioned earlier. 
Storage is always an option but a bad one. You have to go through things multiple times and will spend more than the items are worth over time.
The auction houses and consignment shops will often come and pick up items. You need experienced movers to avoid damage to antiques.
I have seen estate sale folks really rip off the owners. But its all gone at the end of the day. Be realistic up front by going out and shopping for similar items.
Some estate sale companies will take your things to another estate sale if you don't want the event held on your property. Some locations are bigger draws than others, or perhaps the other location doesn't have enough items to draw a big crowd so they combine more than one household.
The estate companies also have buyers that they contact who will buy in bulk. One might want all the rugs. Another the glass items etc. You may know of shops in your area that specialize. You could call them yourself.
There are individuals who will come and haul away everything in exchange for your giving it to them. Be careful not to pick too much of the good stuff out or they won't want to take the junk. The ones I knew about I found from word of mouth. Realtors who handle senior housing sometime know about these individuals. It's a frequent chore they have in getting homes ready for resale after the senior goes into NH or passes. If you get rid of all the good stuff first and then need the junk removed, you'll end up having to pay to have it removed.
Check references of consignment companies and estate sale and auction house businesses. These type businesses are easy for rip off artists evidently as I have heard others complain. It's sometimes a hard way for them to make a living and they get a bit "creative" at times. No disrespect intended. Take photos and "run your traps" at consignment stores to make sure you have either been paid for the items or you still see them on display. If they have the habit of taking your things to their own home, they will soon learn that you will be following up.
I have seen estate sales with things as intimate as nightwear and photos and class rings and marriage license and as seemingly worthless as paper grocery sacks and quarter bags of bone meal (I paid $.80 lol). So don't assume things don't have value to someone. If you don't need the income or need the tax write off instead, take items to resale shops that benefit animals or abused women or churches. Some are for profit but they look like they aren't .Some are not for profit but they discriminate against their disabled employees and pay their executives top dollar. You'll still get your tax write off but if you care about who you are benefiting with your mothers things, check it out. Some won't take things like mattresses and futons, stuffed animals and things that are damaged.
It's a lot of hard work but represents a long life lived so you can see why it takes a while to disperse.
Almost forgot, some consignment stores might give you a credit and let you use it on things you need. Say you need a smaller dining room table. You let them sell a few things and give you a credit. When the table you have been looking for shows up, you use your credit to purchase it.

Susan, Rainmom, and 97yroldmom, thank you for your wonderful advice. I did not know that I needed to watch out for deception with the auction companies, but two of you mentioned it so it must not be rare.

Regarding the tax write off, how does that work? I have two brothers and intended to sell the items and split the money three ways.

Thank you for reminding me to take my time. With my brothers waiting on "inheritance" I feel pressure. Mind you, they are not pressuring me to move ahead. I will be selling my home which has been unoccupied for three years and bringing my belongings here to my parents home. So I also need to list my house and look at moving my furniture etc. in here. I am paying for electricity, insurance etc. on two houses now so that makes me feel pressure to get things going as well. But I will remember to take enough time to make the right decision.

I read about a couple of auctioneers who went to prison for 14 years for fraud. I'm sure most are honest. The tax write off is a charity contribution if you itemize deductions on your income tax. Good luck on it all.