In-laws issue

Dear All Advisor,
My sister has been married for two year(2016). And her husband works out and mostly lives outside. but 2 month after the marriage, sister's in-laws had started harashment. like (In-laws used to put a daughter-in-law in the same room and she was not allowed to go into her room if she accidentally went to her room, she would have been scold and beaten a lot. And speak bad about the girl's parents. And always used to torch the the girl. In every minut in-laws used to tortute Sometimes she was tortured about her clothes, and she was tortured in her physical form and was sometimes tortured with her parents. Despite being the second daughter-in-law, she was given all the work at home and was treated like a maid. And they used to find new ways to get her irritate. But after having a baby girl, the ln-law started becoming more and more problems. And she was also tortured with baby girl. And whenever she used to tell this to her husband, he would have said that settle down with herself. And no response was given. In-laws, the daughter-in-law was beginning to suffer more physically and mentally. In-laws put the daughter-in-law and baby gorl out of the house. When the girl told her husband about it, the husband said that you go to your parent,s house, and when I come back, I will make all right. When the girl's husband came back, he started blaming her wife. Without permission from the girl, they kept all the things of the girl in the rented house. And the girl started living in the rented house with her husband. The girl's husband started saying that I have saved my parents and you can not do anything now. And now he does not call or raises our phone.)

In this case, what should we do to please give the right advice?

Thank you