@Judy498
Probably best to start a whole new thread rather than taking a question onto a 2 year old one - a lot of people will likely miss your question.
Re what to do , if you read further up this thread there's lots of advice about how to proceed for this very situation. I don't see why you shoudl refund anything really. They didn't let you know they weren't coming and you lost the ability to have anyone else stay - why should you lose money for their poor manners and communication?
probably @Helen3 advice best suits you which was
"To be honest in your situation I wouldn't offer them any additional refund, as they were so rude in not letting you know.
I would just message them on Airbnb. Say that it was disappointing to find they decided to stay elsewhere and didn't let you know until you contacted them to see where they were. Confirm that cancellations need to go through Airbnb and they will be refunded in line with your cancellation policy.
Then call Airbnb and alert them to what has happened and confirm that if the guest approaches them for a cancellation, it will be in line with your cancellation policy. When Airbnb sends the cancellation notice, they will ask you if you voluntarily want to give them an additional refund. Just say no."