Drunken aunt is trying to get my brother locked up

jackie
So my aunt lives with my brother ans my mom and she is an alcoholic that has recently statted drinking again. In the past she has gotten extremely violent (chasing mu dad around with a knife, hitting my mom). So yesterday she was mad at my mom so she went and took a bunch of my brothers stuff and locked herself in her room. His plan was to go grt it today along with some stuff hes been letting her use, while she was at work today. She decided to stay jome and told my mom that she was going to antagonize him to get him to hit her then call the cops and get him locked up. Does anyone know of there's steps we can take. My brother is usually able to keep his temper but im worried about if she gets in his face or even hits him first then lies to the cops