Senior citizen harrasment

Sir my mother is living Ghaziabad property owned my father in 1974 since my father died in year 2005 no will was made by him after few years my two sisters filed a petition in the court to divide the property in four parts each of us getting apart now my mother is a senior citizen diabetes patient age 69 years is living in the house from last 40 years since the property is given to a tower company for rent in 2007 in favour of my mother now my both sisters are married but the younger sister and his husband are both living with my mother because of his share and also want to sell the property by fraud they have stolen the property papers and also the tower aggrement papers and divide the rent of the property papers by fraud signature of mother and my also in three shares not giving me my share and they both are daily haressing my mother to give his share to them and beating him several times she had filed a case against them in local police station but no action is taken because they have given money to them what is legal action to taken now