Severe torture by daughter -in- law and her mother

Our mother has been physically and mentally tortured by her daughter-in-law and her mother since 2014. She had made a suicide attempt in 2019 by taking heavy dosage of sleeping pill, but, by God's grace she survived. In the pretext of lodging many cases, the daughter in law has been blackmailing and threatening to kill mother. She is Pressurizing my brother to make her joint property owners by threatening him. Brother, his wife and 11yr daughter are dependent on my parents' pension. They are senior citizens of around 80yrs. Both are patients. The police is very casual and any one can be moulded by the superb acting skills of the daughter-in-law and her daughter. Pl. Suggest how my parents can be saved.