Hello RainGardenSeattle,
Thank you for using Apple Support Communities! I understand that you received an Apple Cash payment from a friend, however the transaction was showing pending and now expired. Your friend is not seeing the balance returned to their account after.
If a payment is cancelled or rejected, it can take typically one to three business days to see the refund depending on the bank or card issuer:
Send, receive, and request money with Apple Pay - Apple Support
If the other person still does not see the refund after that time, I suggest having them contact their financial institution to investigate the status of the refund. They can also reach out to Apple Support directly here:
Apple - Support - Product Selection
Cheers!