Daughter in law is threatning her sister in laws and relatives

The case is : This girl is married to my cousin last year and this year in november she gave birth to a baby boy. From initial days of her marriage, she has given all mental torture to her mother in law. She abused her, taunted her, threatened her of committing sucide and will complaint againt her under domestic violence. My aunty ( her mother in law) was such a sweet lady, she never musbehaved with her. And as a result of this mental torture, 2 days back, my aunty passed away with just month illness. In her last days also, this girl fought with her and gave her mental torture. Now, on after my aunty's two days of death, this girl has started abusing her sister in law and took all my aunty's jewellery forcefully. Also she is threatning everyone that she will complaint against them under domestic violence and put them behind the bars. She abused her sister in law and raised hands on them as well. My aunty's daughter also has right on her property. But this girl is just showing her true face now after my aunt's death openly. What can be done in this case, please suggest Sir/Ma'am.