How to take a legal action against daughter in law for harassing her mother in law?

I had come across an incident in my neighborhood. I have known the family since a long time. This family had 6 sisters and a son. I have not seen any disturbance in their family till now. The family had a good name in the village. Their father is no more and the last two kids were raised by the mother alone. Mother had married her son to her eldest grand daughter. All the sisters and mother had handed over all the parental property to the son. Son was also very responsible and took care of all his duties to mother and family. Recently, during the second wave of covid the son died. After her sons death, her grand daughter started harassing her and humiliated her alone with her mother and an aunt. Since all the property was with her son, now her grand daughter has turned her face towards her. The old lady was having a very tuff time now. She was not allowed to touch her grand children, she was treated with disrespect, she even started getting anxiety attacks and after her loved son is gone there is no one to take care. Now, her granddaughter has taken all the compensations for her son including insurance from his past working company and etc. And her granddaughter has even applied for a legal heir without informing her and later it is found that her name was not included in the legal heir. After her son's demise she has no other hope. Whatever is happening to her seems very unfair. Is there any way to help her legally? Please help.