Brother attempting to take Mom from assisted living. Any input?

I was able to get Mom settled into assisted living, at a very nice place. My brother, 53, who has lived with her all of his life, and refuses to work, comes to the assisted living facility everyday and sits there with her from 9am-9pm. His being there keeps her from enjoying the residents and the activities, and he is problematic with the staff. Mom apologizes for his behavior when he leaves, but will not tell him to move on with his life. She feels responsible for him, and I believe, a little afraid of him. This week, I got a call from the facility telling me that my brother gave a 30 day notice to remove my Mom from the facility to bring her home. She is 90, frail, not able to walk without assistance, and substantially overweight, so ambulation and self care are not really possible. Of course she would rather be home, but my brother is poisoning her mind each day about the people and the facility, and refuses to encourage her to adapt. They are also hoarders, and the home is currently unsafe for her. Afraid that he will try to take her out anyway, I contacted the facility, told them about the condition of the home, about her inability to even access the home due to too many stairs, etc. I am asking that they request her home health care service to perform a home check, to certify that it is in a condition that would not be unsafe. This is not the case, and my brother may not even let them in to examine the property. We are also planning a care conference, at which the findings from all concerned could be presented, and he will hear it from them. I am feeling upset and awful because I know that she wants to go home, but I feel that I cannot allow that to happen unless or until the house can be made safe for her. She requires two persons to assist her in all of her goings on, and my brother has told her that he can do it by himself. I have to stop this, and want her Dr. to also weigh in on her ability to be safe and maintained at home. Does this all seem reasonable? I am afraid for what my brother might try to do, but I live 8 hours away and can't monitor the situation regularly. He won't even let me in her house, and has hidden her keys away from me. He is unstable, and refuses to listen to anyone. An example is that this week, he got into an argument with the caregivers because he insisted that Mom’s used incontinence products be stored and kept in her room rather than being thrown away for health and safety. This whole thing is making me kind of crazy, and I am really afraid for Mom. Am I approaching this in the right way? Any input would be appreciated. Thanks so much.