If I were a bridesmaid I could never imagine asking a bride who had to cancel for a refund. I am sorry your wedding had to be canceled. I would say in the interest of preserving friendships I would offer the refund, but I would hope most wouldn't take it.
So, my friend cancelled her wedding - not due to the pandemic. They broke up. I spent $200 on this bridesmaid dress that I can’t even pick up because it was $300 so they said I have to pay another $100 to get the dress - which they never even received my measurements, but that is besides the point. She never offered to reimburse me and I think it’s super rude. So - offer the refund. If they decline then that’s on them. I would have accepted my $200 deposit reimbursement...lol best wishes!
So sorry you had to cancel! Yes, I would definitely offer to refund your bridesmaids for the dresses. It is up to them whether they would like to accept the offer.
I agree with everyone else that you should offer to reimburse them. And it's fine if some take the money, but some don't. The ones who take the money are not bad friends. They literally wouldn't have spent that money in the first place if they hadn't agreed to be in your wedding, so it's not fair to penalize the friendship now.
I'm so sorry your wedding was cancelled. Since you made the decision to cancel, yes, you should definitely offer to reimburse all of them for any costs they have already incurred. Each one can then decide whether to accept or forgo your offer.
You should reimburse them for the dresses. They only bought them because it was a requirement for standing up in your wedding. It is your responsibility to reimburse others for any costs they incurred to be part of the wedding that is no longer taking place.