Your post was a little hard to follow, I'm going to be honest, but I think I got the gist of it.
You want/expect your college-aged daughter to come back to your house each night while she's home on breaks, yes? OK, so you've already spoken with his mother, correct? You've spoken with your daughter? You've spoken with the boyfriend? None of them cares is what I'm getting out of this since the behavior is still going on.
IMHO short of withholding payment for college &/or telling her she is not welcome to stay in your home any longer, I'm thinking there's pretty much nothing you can do about it if you've already requested the behavior change & it hasn't happened. Technically you're talking to 3 separate people who are all adults, albeit disrespectful adults, but adults none the less. It doesn't matter whether or not any one of us on this site agrees with your reasoning, it's yours & yours alone & you are the only person in charge of how your household is run.
My parents made similar rules for me. I spent the night with my (then) boyfriend pretty much whenever I wanted to. I worked full-time & attended college full-time. I paid for my own college, books, car insurance, clothes, toiletries, etc., etc., etc. I did NOT pay them rent as they did not request it as long as I was a full-time student. They told me not to stay at my boyfriend's house & if I continued to do so I could leave their house. Guess what happened? I left their house. Yes, I went back a year or so later, but only for 3 months while my leg was in a cast due to a shattered ankle. Once that healed, I got married & moved out for good.
My point is this: make your decision & stick with it, but know that if you make ultimatums you need to ensure you're ready to follow through with them & that she may still choose a path you don't like.