Hi @Blair-and-Steve0,
First off, if it was an Instant Book, you did not approve the booking as you do not get a chance to approve it as it gets automatically approved.
In any event, there are several ways of dealing with this.
1) Follow your cancellation policy and have her cancel and she will be refunded the amount according to your cancellation policy.
2) Have her cancel and offer to refund any money not paid out if you are able to find a replacement guest.
3) Choose option 1 and offer to provide a credit for a future stay in whatever amount you wish (this is something you would need to track as Airbnb does not provide credits
4) Provide her a full refund
5) Have the guest continue with her booking.
There may be other options but it really depends in what you are comfortable with.
Cheers
Dave
David
Superhost Ambassador ~ Host Club Community Leader ~ Community Expert ~ Experienced Co-Host