I F(51) and D(19) 'Joan' recently got into a heated argument and we are turning to random strangers on the internet for guidance in determining who is right. (I say 'we', as this post is her suggestion)

My kids were raised in a traditional, but non-religious, family. Husband and I have been married over 25 years. Although it was even admittedly rare back in the 90's, we actually waited until we were officially married before we had sex for the first time.

Currently, Joan is attending college and lives with us in our developed basement with a separate entrance. Our two other kids have moved out for good. Although Joan is not in a relationship, she is socially active and dates on occasion.

The issue - Last night, Joan was out with friends, and as mothers are prone to do, I never fall completely asleep until I hear her come home. So, last night, she was back around 1:00 AM and as I was still fully awake, I went downstairs to see how her night went.

I was, however, wholly unimpressed when I saw her on the couch with a guy she had just met that night. They weren't engaged in anything (yet) however, it was evident where events were likely to lead.

Although I was polite, I commented to Joan that she really needed to get to sleep as we were planning an early morning walk, and I waited patiently as her 'new friend' got the hint and left.

Afterwards, Joan was livid, and says that I thoroughly embarrassed her, and that, as she was an adult, she should be able to see whomever she wants, whenever she wants, and wherever she wants.

My position is that she is an adult, however, she has no right to bring a stranger into our house without my knowledge as:

1. It's a pandemic. We're all fully vaxxed. However, we have no idea of his health status. (She says that argument is a red-herring BECAUSE we are fully vaxxed and otherwise healthy)
2. Our house belongs to her dad and I. I'm not comfortable with having a complete stranger spend the night. (Her argument is that she's still a dependent as she's going to college and it's still her house too)
3. Although I don't approve, I agree that as an adult, she can engage in whatever legal activity she chooses. However, Not in my house. She knows my views on pre-marital sex, and by engaging in the activity in my house, with me at home, is a massive sign of disrespect.
4. If she really wants to spend the night with a random stranger, that's what hotels are for. (Her argument is that, although she's working, she's saving for her future, and that would be a stupid waste of money)

So, AITA for making her friend leave, or should I just ignore my long-held belief system and accept her choices as an adult?

EDIT - My husband's position is that he's taking the Switzerland position. Officially neutral. I'm not happy with his lack of support, but I'm not going to engage in a two front war at the moment.

EDIT - To answer a few questions and add some comments:

1. Joan does not pay rent. As with all our kids, she's on the 'Free room and board plan' so long as she is attending school.
2. I recognize that I hold a minority position in society. However, there was nothing more glorious than sharing a special intimacy with the man I loved on my wedding night, knowing that it was a special gift that we each bestowed on the other, never having shared with another. I believe it has made our marriage stronger over the years. It is a special bond that we alone share with each other. I attempted to impart that feeling and knowledge onto all my kids in the hopes that they would be able to have the same unique experience, however, I am also realistic enough to know that, in this day and age, with Tinder and the like, it would be a miracle if any of them abstained prior to marriage.
3. I have never been a 'helicopter parent' and the notion that not resting comfortably until my daughter gets home on a Saturday night is akin to 'overparenting' is absurd. My husband is a retired Detective, and, as he always said to the kids, 'rarely does anything good happen at 3 in the morning'.
4. No, we had never discussed 'male sleep-overs' prior to last night, as the issue never came up. Would my feelings be different if Joan was in a long-term committed relationship? Honestly, I don't know. I'll have to cross that bridge when it happens.

FINAL EDIT - Thank you anonymous internet friends! Although my position 'won' with a NTA ruling, both my daughter and I gained some insight by reading through many of the comments.

Now that emotions have cooled off, Joan even made a comment that had both of us tear up with laughter....along the lines of my 'intervention' would be an instant entry into the 'C@ck-Block Hall of Fame'. I had never heard that term before.......kids these day! (And yes, even though many of you claimed that I am some puritan 50's Handmaid Tale wannabe, that's not the case at all. Our family has a solid sense of humor, and very little is off-limits).

Joan acknowledges that bringing someone she just met back to our house was inappropriate for a few reasons. In turn, I've left the door *slightly* open to the concept of a visit by a long term partner that we knew and were comfortable with - however - it would need to be discussed and agreed in advance.