Roomates stole home surveillance cameras?!!?

My mom rented a room in her house that she also lives in. These people moved in and have totally violated her home and wont move out! She has given an evitiction notice for brining in pets not agreed to on the contract, so she gave them a notice to remove pets or move. They did not do this and have now been given an eviction notice by the court. An attorney advised my mom to put nanny cams in her house in legal places and outside as well to get proof that they still have animals and to prove that these people are haring and intimidating her. She came home and her cameras were GONE!!! They stole them!!! And i think they called the police. But can't my mom have video surveillance in her own home as long as its not in the bathroom, or in their room? These people are mooching off her and dont even have jobs and the guy already has a criminal record. My mom is having the police come to make a report. She can have cameras on her own personal property, correct?