Dad passed away. Wife and 4 kids are alive.

Hello, I am from bangalore and have a complication. My dad passed away unfortunately some 2 years back. He has wife and 4 kids alive (2 sons and 2 daughters) All married except one daughter. My brother and sister (Unmarried) has taken away all the property documents and ornaments. My mom is struggling to get back al-these as my Brother wants to loot everything and he is not ready to talk about althese. Question 1 - Is it possible that he himself can sell the property on his own without taking the consent of other successors? I know its not possible but still is there a way to do? If yes then how can i know that he is going to sell/ already sold. I just have the property details but no documents. Question 2- What will happen to the ornaments. Can we fight for it? Question 3 - Mom is going into depression and he is least bothered about her. She wanted everything to be converted to her name. And wants to stay independent. is there a better way to deal this than going through complications in court etc? We already did an internal discussion about this to him. He says I will am not interested. Thanks