How is ancestral property succeeded without will

My grand father has 3 son,1 daughter and grand father wife. when grand father passed away the property separated by head of the family(cousin). Property details: 40 Acres agricultural of land in town. 3 sons taken 10 acres each. mother and daughter taken 5 each. 100 acres agricultural of land in village. 3 sons taken 100 acres without giving to mother and daughter. 2 acres of commercial land. 2 sons taken 2 acres without giving to mother and daughter. 2 Houses 2 sons taken 2 Houses without giving to mother and daughter. they have taken signatures of mother and sister. recently mother passed away without any will. now bother are planning to take 5 acres of land without giving to sister. Now sister can file case against to brother and head of the family member who separated property. if we file cases now can we get justice of old property separated long back(30years) head of the family member