Siblings do not speak; What should I do?

I am one of 4 children- 3 daughters and a brother who is the oldest. My mother is 93 widowed, and living alone. She cannot care for herself anymore. Attempts to discuss living alternatives (moving in with one of us, moving to a home in close proximity to one of us, assisted living, etc.) have been a total waste of time because she cannot/will not make decisions. My single brother (from out of state) flies down and visits every few weeks, and we appreciate that. We daughters live closer to her, but she has hoarded. She does not want us there because we tried to convince her to let us clean and organize. There is stuff from floor to ceiling and wall to wall. No room at the kitchen table to even put down a plate. There are paths to get from one room to another and all other rooms are full and no room can be used for its purpose except the bathroom.

We gave up on trying to clean, but we tried earlier this year to get our brother to discuss her declining condition with us and with her and hopefully, convince her to find a safer alternative. She trusts him the most, so we needed his help. The $#*! hit the fan between siblings and years of resentment came to the surface. As the youngest, I was not much a part of that screaming argument, however, my brother is not speaking to any of us. My mom seems to have personality changes- she is being mean and she seems different. She seems to think we were trying to put her in a nursing home because she keeps saying things like "Why don't you go volunteer in a nursing home?! See how they abuse old people!!" I was not trying to put her in a nursing home. One of my sisters suggested assisted living or at least looking at one. I suggested adding a room addition to my home and letting her live with me- at least someone could come and help at my house- she won't allow ANYONE in her house- not for any reason.) It is taking an emotional toll on me because I no longer feel loved by my mother and I feel betrayed by my brother. (I believe he is using his role as "the good one" to take all the inheritance while maligning me and my sisters.) All three of us have offered to help her- I offer to bring fresh milk and produce or whatever she needs, I offered to help her bathe once a week, I told her she could live with me...but she tells me not to come. (It's too far... You're too busy...I have everything I need...and so on.) She has never really allowed me to help. She actually gets mad when I come because the house is so full of stuff and clutter that she does not want my kids to come and she does not want to tell me not to bring them. I can't win. There is a (perhaps) unhealthy or at least odd relationship between my mom and my brother. He never married and never had a relationship that we know of. My mom has pitied him and been pining over him all his life. As a result my oldest sister (close to his age) always felt unloved. I'd call it sibling rivalry except for the fact that it has become painfully obvious that my mother really did favor him because he continues to evoke her pity as a 63 year old man. I don't expect my mother to live much longer, and I have no idea what I am supposed to do when that time comes. What do siblings who do not speak do when their only remaining parent dies? I don't know if she is leaving anything to me. If not, that is okay but I don't know. I hoped to get the childhood pictures of myself if nothing else. I also don't know what to do if I am the sibling who finds that she has passed away. I do not know any of her wishes because she has never shared them. I think the only one who knows anything is my brother, but we do not speak. I am wondering if I should end my relationship with both of them. What do people do when this kind of thing happens?