POA abuse craziness, any advice?

My sibling took custody of mom a year ago, without informing the rest of siblings. During which time we have had restricted visitation and no updates. Mom is terrified of him and fears for the safety of all of her children. Recently she was allowed to stay a week with me and she has been pleading not to send her back to him, she told me about him mistreating her and spending all of her savings. She has revoked their POA but he calls with threats and keeps calling police on me for kidnapping. The nursing services had asked that she be placed in my home for at least 30 days because of the storms, but he is trying to take her by force anyway. All of this happening in one week. I must protect my mom, any advise.