My grandmother is a toxic person. Can’t tolerate her anymore and I’m getting depressed. What to do? How can I control her anger?

I am an Indian woman and live with my Mom, sister and grandma (Dad’s Mom). I lost my Dad 4 years back and lost my grandpa 5 years back. So, you can guess, from 2013 still now we are passing a very hard time. On one hand, I lost my father and on the other hand my one and only Aunt ( father’s Sister) is tring so hard to grab all our properties unethically. After my Dad’s death till now I am fighting for my rights, my sister’s rights and for my mother’s rights. On the contrary, our grand mother (Age 75+) is just not supportive at all. She is a toxic person. When I was a toddler one thing about her I can remember is, she is screaming (by using slangs) with my mother for no reason, screaming with helping hands and even with my grandpa. Still now after 25 years, she can’t tolerate my mom! My mom is getting weaker day by day. Myself and my sister are getting depressed. It feels like she is monitoring every movement of us and she is trying her heart and soul to find faults of us so that she can use those slangs again! She is also helping her daughter so that she can get those properties. Whenever we go for shopping or for some outing, she just doesn’t like it at all. Noted that my mom is a home maker and my grandmother just want my mother as a slave and treats her like that, nothing else. Even my dad also had some bad experiences with her which he had shared with us. My aunt does not call her at her home! You can just imagine how disgusting she is! Today also, she was screaming at us for no reason. She does not want to give respect to us but she wants respect from us. How it possible? I am so very depressed and I feel really sorry for my mother that she didn’t have a great day after her marriage. But still she is trying so hard to make her happy! When my grandma insults us, my mom doesn’t give any reply and shows her respect and my dad was same. But still my grandma is doing the same thing again and again. Grandma also insults the guests who are from my mom’s side but she is very nice with outsiders and pretends like she is a very nice person. My mom’s life is in hell. Please give your suggestions and help us! I'm dying! She is not mentally disturbed, physically fit, self obessed and selfish person! How can I control her behaviour and can save my family?