Your father has no right to throw your mom and sister out of the house. If your mother files for divorce , only then she may be able to claim property rights on the property.How did your father get this property..? The supreme court has given a judgement some two weeks back, that a divorcee cannot be sent away from matrimonal home.
Your mom can file a case under Crpc 125 for maintenance only .If you or your sister are below 18years of age you can be added as a party in this case and seek for enhanced maintenance. Only upon the failure to pay the maintenance amount , you may go for attachement of property.