Friend's step dad wants to have sex with her?

So last night I was at my friend Kaylee's house. Her mom works night shifts on Saturday so we there alone with her step dad. We in her her room on the computer while he was downstairs getting drunk. He came up to her room, so drunk, and said "Kaylee I want to get in your panties" and started laughing. She just kept typing and totally ignored him as he kept saying it for like 5 minutes then he went back downstairs. I was wtf and she said "he gets drunk every Saturday and says s*** like that" and I said "tell you mom. He could do something to you" and she said "that's just the alcohol. He's drunk not stupid. I'm not scared on him" but I think she should be. Him and her mom have only been married like 5 months and they've only known each other like a year and I KNOW him and Kaylee don't get along. She's alone with him every Saturday so I'm concerned for her safety but she's not worried. Her dad is dead and her and her mom are not close so I know she's not going to tell. Should I just tell her mom? I mean, he could hurt her right?