My SIL (86) complains about her daughter, who purchased a place so that the SIL could stay with her.

My SIL who is around 86 y/o complains that her daughter does not call her to let her know that she is alright and when she will be home. She says that her daughter is mean. More background--My SIL was living in her own apartment, with her daughter living across the hall from her. My SIL started complaining that someone was coming into her apartment. In order to solve this issue, her daughter purchased a condo apt. so that her mother could live with her. She took her mother by the condo to make sure that it was ok with her. She told her mother that this would be the last time that they would move. Her mother seemed happy. She has her own bedroom. They have been there for approx a year. The mother does not want to go out to mingle with other seniors. She stays in the apt. unless her daughter takes her out. She sits and looks at tv. They have a cat which she calls her children. The daughter makes sure there is food there. There is a housekeeper that comes in. My SIL's brother and sister call her daily. Her daughter works. She complains that her daughter does not call her to let her know that she is ok. She says that her daughter is mean. The mother says that she would not leave her children(cat) the way her daughter does. The daughter is with her most of the time. Her brother asked her if she had expressed to her daughter that she would like for her to call, because she worries about her, and let her know that she is ok and about what time she will get home. My brother tried to explain that it takes time for her to get from work to home. No matter what he said, her main focus was on her daughter not calling. He also tried to explain that it gets darker sooner now, and it is not as late as she thinks it is. This has happened times before. It seems that she is so negative. It seems that the mother does not appreciate what her daughter has done. She, my SIL, says that she has to feed the children(cat). She just wants to stay in that apartment, does not want to mingle with other senior citizens and depend and then complain about her daughter. What options are there? To help my SIL as well as her daughter. I know living with a parent like this can be so stressful. By the way--The daughter is the only child. Any help is appreciated. My thought is to not allow her to continually criticize her daughter. To ask her "What does her daughter do that indicates that she is mean." Would she prefer living somewhere else, as assisted living, etc. When is the last time that she said "thank you" to her daughter. And that if she feels this way toward her daughter, then she is probably exhibiting it in the way she acts/treats/talks to her. Please help. Thank you very much