Moms jailbird BF moving in - teen daughter scared. What can she do?

One of my teen sons friends is in a tricky situation and I am trying to help her figure out what she can do. She is fifteen and lives with her mother. Mom is/has been involved with a real slimy dude who has been in & out of jail. I am not sure what the most recent charges were but he was in for six or eight months this time. Mom is on lots of meds and is pretty flaky. Always says she is done with Prince Charming each time he goes to jail but then goes right back to him when he gets out. This wasnt such a problem for my young friend before as she lived elsewhere. Now she has nowhere else to go. I live several hours away and cant afford to try to move her in. Is there any way she can get a protective order to prevent her mom from letting this guy move in with them when he gets released from jail THIS time? We live in Texas if that helps. Thank you for any advice.