If a child come back after demise of the father…

Hiii sir, I had lost my father about 1.5 yr back. Me, my mother and my father lived together throughout the period of my 24 years… I have my brother but he lived with my maternal mother., after asking for her son my mother tried hard to get him back but she didn’t gave our brother… as he now hated their parents he never came back .. inspite of all my parents paid all expenses of my brother to my maternal mother. But now Right after my father died he came back to our home…. We spent money on his marriage we did everything and now he is doing all wrong things to my mother… mental peace is gone after he came back he and his wife are torturing my mother..,, I am handling everything since the day my father died. And now he his wife my maternal mother Joins together doing living in our home… What can I do to sort things., I am worried that after watching all of these things regular fights and abusive behaviour My mother heading towards depression. Please help me in that. My email