Dirty friends that like my mom

I am 18 years old and I live with my mom, father, and brother. I have a few friends that are always over at my house during the week. The problem is that a couple of my friends ages 26, 23 are always curious about my mom. They ask me questions like "Is she home?", "Why don't you tell her to come here?" I have a feeling that they are attracted to my mom.
Background Information about my mom:

- 5'8
- 38 years old

My mom has a decent body because she works out at the gym 4 times a week. She has a flat stomach, long black hair, tanned, she also has big boobs with a saggy ass. She always waxes her arms and legs because she likes to look nice.

My problem is that she isn't happy with my father. It might be because he's never home and she doesn't have much interaction with males.(Im never home also) She always spends time talking to guys at the grocery store, gym but LATELY SHE HAS BEEN SPENDING a lot of time at home. My friends ALWAYS stare her down because she doesn't wear a bra half the times which makes her breasts show through her tops. She wears short skirts, yoga pants, beach shorts because she is always working out and at home she feels safe to wear such clothes.

My friends always stare at her and tell me that they want to f*** her. I get pissed off but they keep talking about it. When they talk to her she doesn't realize it but her body is always exposed. FOR EXAMPLE: When she wear tank-tops her clevage is exposed and when she wears yoga pants, her butt shape is exposed for others to look at.

I haven't told her that her wearing those clothes attracts other people. WHAT SHOULD I DO?