What can I do If my mom's sister starts trouble over new POA?

Taking care of mom since 15. Had durable poa and had to put mom in long term care facility. She is bipolar and diabetic and her last 3 breaks she had become increasingly violent and unconcerned about her own wellbeing. Her family has never wanted anything to do with her except to make fun of her and tell me to not let her embarrass them. But these are people with money and connections and they really only care how things look. They don't know anything about mental illness or the care system and they think if you throw enough money at something it will go away. So it was looking really bad when things happened to get my mom in the long term facility. We had a all day man hunt because she ran off in the woods and no one in the family cared. But it's a small town and people would ask me if they were helping and I would be honest and say no. Next thing I know my mom's half sister is threatening me with all kinds of things if I didn't allow her visits. Now my whole life her and my mom have never gotten along we would see her maybe once every couple of years during summer. Her husband grew watermelon and they would bring one to "visit" but actually they would stay 15 min. And then spread gossip for the rest of the year. It was so bad that before going to the facility my mom was saying things like her sister needed to die and be skinned by dragons and her flesh cooked. So I had them taken off the visit list but the threats were so bad and my family doesn't have money to fight them that we discussed it with her Councelors and agreed on supervised visits. It seemed ok but then her brother got divorced and moved back and one of them who has mental health issues of his own along with abuse and drug issues started visiting. Meanwhile mom starts insisting on home day visits and the Councelors think it might help so we do. But after 3 visits it becomes clear that it's a bad idea. She starts locking herself in what was her room and talking and banging around to a much lesser degree but like when she was home. The decision is made that something here is a trigger and home visits should be limited but then the workers at the facility change and later we would find out one of the is with a group trying to get people out of long term facility's and so they have joined up with the brother and gotten mom to revoke my poa. My mom was doing fantastic at the facility. She was stable and functional and that's when she is most dangerous because she is clever and very intelligent and until the condition is really bad she can make most people think there isn't a thing wrong with her. So this APS worker came who was New to the situation and said mom was stable enough to decide and that her brother had promised to take care of her. Even stating he had a daughter with bipolar and knew all about it. I expressed to APS who have helped us several times over the years that it wasn't good and that he was playing a game and that they wouldn't take care of her. That my fear was she would get sick again and no one would be there. But that after almost 20 years of taking care of my mom and going through what at times became a living he'll and after 2 years of having my family just attacked by her siblings I couldn't start over if they took her. I was assured that wouldn't happen and that home checks would be done. Later we found out the home checks never happened and now after three years of trying to rebuild our lives my mom has been calling me because she has been taking care of herself but she is having health issues and the siblings don't want to help her anymore. Even to where she needed to go to the ER but the other brother who lives with her said he had done enough for her and wouldn't take her. She has been weak, dizzy , very faint, lack of equilibrium and almost unable to walk. The sister I was formerly talking about took her to the hospital where they did tests and said she had vertigo and a sinus infection. A week later the same situation but now only the brother that got her released will take her. So now she has a bad inner ear infection and her sodium levels are extremely low. Both of which explain all the symptoms but they came to see her the next day and had decided that since an EKG and a cat scan has come back clean the whole thing was made up and she must be off of her meds so they want to take her to her doctor and have her recommend a facility or phsyc ward. But that she needed to decide on one of them for her poa. She is terrified and called me to tell me she didn't know what to do. That they were gonna force her into this because they were tired of helping her and just wanted rid of her. Plus she is afraid they will take all her money so she wants to give it to me before they do this so I can take of her. Then she asked ifbi would take her poa? After talking it over with my family we feel it's the only right thing to do. And we do fear what they will do with her if they get it. But I'm afraid they may walk away but may not