Can We Get Maintenance From Father's Family Members?

My dad has been abusing me, my brother, and my mom financially, emotionally, and verbally, and he has physically assaulted my mom. For years, he didn’t let my mom work, though she rebelled and started earning. When I was born, he fought with her because I’m a girl. My nana and nani told her to divorce him, but she stayed, hoping he’d change. His mom constantly abuses my mom and manipulated him into giving away his property to his elder brother, who now denies his share. She also took all his FDs and claims they’re hers. My dad has lost his memory, refuses treatment, and wants to quit his job. If he does, my mom’s income won’t sustain us. My mom wants a divorce and alimony, but he gives his money to his mom. Can we press charges against her? Can we get maintenance from his brother and mother if he’s declared mentally unfit? His mom blames us for his mental condition but is the one who manipulated him and drove my grandfather to suicide. How do we escape this?