What are the rights of a daughter in mother's property?

My mother obtained property (house and land) through her father. I (Kamla Sharma) have been residing with mother and have been taking care off her through out life. Not only me, beyond me my husband and three sons and one daughter also taking care off her time to time. Only son of my mother was not residing with her. My brother’s family i.e. his wife, son and daughters hated my mother throughout the life. Even brother/ any his family member come to see my mother only one time in two or three years for few hours only. After her death my brother (Badri Prasad) prepared will (unregistered) with the help of three person as witness without my permission. And capture maximum part of my mother's property. Further, he capture/ transfer all property in favour of him by using corruption of registrar office. How can I obtain half part of my mother's property? Although, my mother was unable to make signature. So, in will there is only thumb impression of my mother. This is also suspected that th