Hello @Sean-and-Brittney0,
All guest payment issues are a matter between Airbnb and the guest.
When the guest cancelled their credit card they should have registered a new one with Airbnb.
If you wish to refund the guest then you can do so via the resolution centre. Airbnb will then handle the refund process.
If you have already received payment for that guest then Aribnb will deduct the refund amount from your next guest payment.
One way to find the resolution centre is to type "resolution" in the search box under "Help". Then click on "Visit resolution centre".
You then select "Send money" and then select the reservation in question.
Steve.