If the guest cancels you can call Airbnb and request they get a full refund.
I have done that for a regular guest who had to cancel. But in this case Airbnb should do it for you and call it extenuating circumstances.
Lastly, I once booked an Airbnb and the host had a guest who got her dates wrong. So she ran to Ikea and bought an extra bed. We are all still friends after that.
Wish Aiebnb understood their platform won’t survive an IPO if they don’t give hosts more flexibility. We are their backbone.