My uncle, his wife and his parents used to live in same house. My uncle's wife is abusive person and

My uncle, his wife and his parents used to live in same house. My uncle's wife is abusive person and always caused troubles to in-laws. So my uncle and his wife moved to a different house in same village. Recently my uncle died. The wife moved back in with the in-laws house with three children. She does no work in the house and doesn't take of the children. Everything thing related to children studies and school is done by father in law.Now she started verbally abusing in-laws in public and mentally harassing them. They lost their sleep and peace because of her. She is threatening them with suicide and she says she will write suicide note stating that her father in law raped her. She also threatens that she will commit suicide along with children. She is also beating children. Family is hindu. I have no idea if this family is considered divided or undivided family. I want to know how can the in laws take legal custody or guardianship of children and get to rid of her from the family.