I've read the whole thread - whew!
Hate this assumption that boys are always a danger.
This. I'm the father of two boys (grown up now), and I hope they always acted respectfully towards girls. One of the things that I think is really nice for teenagers growing up today (and so different from when I was that age) is that it is seen as perfectly normal to have friends, both girls and boys, without any need to get into a romantic relationship.
I think the OP's husband is treating his daughter as a child. Some PPs on this thread clearly think so too. She isn't. Legally, yes ( someone is bound to point this out) but not in any realistic sense.
In my experience, (35 years teaching, of which 10 as a houseparent in a boarding school, plus two spells as Year 9 form tutor in girls' schools, and extensive voluntary work with teenagers (Scouts, DofE)), girls do a huge amount of growing up between 13 and 14 (so Year 9). More than in the next two years put together.
So what she wants more than anything right now is to be an adult. She isn't, of course, but she is far closer to adulthood than childhood, and the adult privilege that she wants especially is the right to make her own decisions. They may not be the best ones at first, but the only way she will improve her decision-making skills is to practise.
The role of a parent is to use their greater knowledge and experience to predict the outcome and be ready to catch their offspring when it all goes pear-shaped. Not to wrap them up in cotton wool. It's all about risk assessment and risk management - they have to learn to do it for themselves.
So, I would have let her go. As some other PPs have suggested, I would have a phone code so she could contact me if things didn't go according to plan. And the OP needs to get across to her DH that he is being overprotective. Otherwise, the next time she barricades herself in her room - and is "safe" - she'll be out the window with her other phone (without the tracker app) and her dad will be blissfully ignorant.