Hi @Angela4124
The way I understand your question is that the booking has been cancelled and refunded. However, there is now an extra guest fee that still needs to be refunded. I went to a cancelled booking on my own profile and noticed that the "Send or request money" option has disappeared, so I think you're stuck because this obvious solution is no longer an option on a cancelled booking.
Here's what I would do: go to the cancelled reservation and copy the confirmation code. Then go to the Airbnb Help Center and ask that they refund the guest the extra fee, pasting the confirmation code there. I think it should be easily resolved.
It's nice of you to refund the guest in full and I hope you manage to book some of the cancelled nights.