@Karen-and-Mike1 However, they both contacted me to say I need to approve the cancellation request."
There is no need for a host to approve a guest cancellation. DO NOT accept a message saying the guest wants to cancel and asking you to approve it. If you get one, decline it. If you accept, it registers as a HOST cancellation and you will be penalized by Airbnb.
The guest can cancel from their end- advise them to do this. The only reason guests do this is because if they cancel themselves, they may not get a full refund. Don't fall for this trick.
If you are amenable to giving them a full refund if Airbnb doesn't, you can tell them you'll refund the the rest when you see a payout for their reservation (don't refund before this, because they may convince Airbnb to refund in full, anyway) Or tell them you'll refund the rest if you are able to rebook the dates, but in order for that to happen, they need to cancel ASAP so the dates unblock and can possibly be rebooked.