How do I help my mom in assisted living when she is very agitated? I live far away and she calls me 3-4 times a day.

I live far away and she calls me 3-4 times a day, blaming my brother for putting her there (In prison, when she was fine living at home). My 2 siblings and I made the decision because of her mental decline/dementia. My brother just turns off his phone after dinner... She'll say "They aren't doing anything for me that I couldn't do myself", I worked long and hard for my house and now I can't be there. I don't have my car here so I can't go on drives", "I call your brother but he just doesn't answer" I talk with her soothingly and say "I wish you could go home, too" or "I know, it's a hard adjustment", "we wanted you to be safe", etc. People say that when they see her in the day, she seems to be ok there and has even said to a friend that she knows she should be there. I know the night time angst is probably sundowning and Sundays don't follow a routine as much as the weekdays, but I wish there was something more I could do to help her with her anxiety and agitation.