My question involves landlord-tenant law in the State of: California

To simplify, I am subleasing a room in a home from two women (sisters) who are renting the home from the owner. My contract states that they are both residents of the home, however, in December one of the sisters moved out (causing a bunch of other problems that can be elaborate on if necessary). As a result, another woman, whom I do not approve of because I feel she is a thief, is moving into her room. Now, the other sister states that she will be moving out as well. Is my contracted voided because of their decision to leave the home? Can they move in whoever they want without my approval? Can they leave the home without my approval? Do I have a say in who moves in? Most importantly, does my contract still stand now that the women whom I am renting my room from do not live there anymore?