I too would go with option 3. Although, given that you've had no trust issues with her, I would be very reluctant to take her key away. As long as you've spoken to (and trust) the parents of the girl she's staying with, and spoken to your DSD about what's expected of her, things should be fine. I think that taking her key away, when's she's given you no reason to do so, would be really unproductive, trust-wise. BUT, you know her best, ultimately you guys will know what the right thing is.

I understand her not wanting to go, but I definitely do not think you should stay home because of that. No way. I hope you guys can work it out, and have a great weekend