@Linda5000
First, so sorry about your situation...
There are some extenuating circumstances where Airbnb will not charge fees for cancellations under their extenuating circumstances policy. Not sure if your situation would qualify. It would have been better to contact Airbnb and ask them if your circumstance qualified and if so, have them cancel the stay for you instead of you doing it. If they granted that, it would have prevented the fine and other negative consequences (Superhost stats affected etc.) Of course, always notify the guest via message regarding the situation (sounds like you did). Airbnb could have also helped the guest find another place to stay as well:
Cancellation - Extenuating Circumstances
https://www.airbnb.com/help/article/2022
Cancellation Fees/Fines
https://www.airbnb.com/help/article/990

Guest Refund Timelines
When a guest receives the refund depends on the circumstances and what payment method they used. If they used a CC, it can take up to 15 business days (according to Airbnb). Airbnb will sometimes issue an immediate credit to be used within 72hrs, but they would have had to been involved in the cancellation process. This is to help the guest immediately book another stay if their check-in time was very close to the cancellation.
If a Host Cancels
https://www.airbnb.com/help/article/170
When You'll Get Your Refund
https://www.airbnb.com/help/article/1967
Tracking a Refund
The guest can track their refund status in the App:

Let us know how it goes...