@Jerry391 it's going to be very difficult to get your money back from Airbnb. I would keep hounding them though: try them on Twitter @Airbnb help if you haven't already. Ridiculous that they would blame you for the guest's behaviour, which is absolutely wrong.
Unfortunately, there is no way to pre-emptively prevent a bad review. Hopefully they just won't review you. Be sure to review them honestly: tell your side of the story both in your review of them, and if they review you, in your response to their review. As a fellow host, I would absolutely want to know how they had acted in this situation.
For the future, is it possible for you to set up a smart lock so the code doesn't become active until the reservation has actually started? That's what I've done on my property and it works very well.