How can I protect my mom and keep her from assisted living when my brother is fighting me?

I'm scared she broke her hip a few months back and DPOA for health and finances so I could cover health if needed was given to me - my brother who had documents previously filed false charges with APS that I was stealing money from her they investigated her accts and my husband and I were both investigated there was nothing stolen so there was nothing to find. These 2 never even showed up when she was in the hospital or rehab but 3 months later when they found she had given me the documents of DPOA. I am here for her 5 days a week, sat and sun have a company send in caregivers and she has a lifeline. I get her groceries, set up her meds for her, cook her meals make sure she eats, clean house, laundry, do her Phys therapy in home exercises, take her to senior center, and other places, change cat box etc.. basically everything. He has contacted APS 2x filing literally false claims aginst me. I got all certificates and passed all state exams for home care aide with hopes that would settle them nope, they feel I should be here for free APS said absolutely I can be paid. I receive min low caregiver wage. Last time here he pushed me into a door as he came in with both hands I was not harmed but it made a sound. Mom came out on her cain he made her go into her room and called my sister ordering her that she has to go into assisted living and conceeded she can have a caregiver just not me. She got very upset yelling she wanted me not anyone else. Mind you shes 95. Shes been well cared for, I have done nothing to deserve this but get those documents. Tonight he is outside the house has flown in from Alaska and I'm afraid to even go to sleep, esp. after reading mythreesons post. Hes a bully his wife works for Social Services in another state and there is a lot of money in the estate. I would love that she donated it to charity over this but that's not for me to decide. I forgot to mention my brother is a gambler. He and his wife argued with the social workers on a phone conference when mom was to be released from rehab that she should be kept in assisted care there when the state workers here found her competent to go home and shes had 3 competency tests with her doctor since and been declared competent to be in her home. I don't keep her from talking to either of them, and don't want him here but I don't see I can keep him from seeing his mother. Right now hes flown down from AK and is waiting in his car for morning. He has contacted my own children and their wife's trying to convince them that I am in the wrong for helping mom and she would be much better off in assisted care. She begged me to come here so she could go home. Everything I have done her has been to help her. I believe he will do anything to regain control I really need advice and help now with him outside the door. I don't want control but there is no one else in state that can be here for her and make sure she has the medical care if he puts her away and/or gets her declared incompetent he's indicated in the past he wanted to sell the house which is in an area that houses have gone up in value beyond belief. Help!!!