Is a refinance of a B&B considered HMDA reportable if the owners occupy it also as their primary residence?

It would depend on what your original mixed-use test told you. Did you record the original purchase (assuming it was your bank that made the loan) as a purchase for HMDA? If the purchase was exempt because the property was considered commercial, then the refinance is as well. If your bank wasn't the original lender, then i would employ the mixed-use test now to determine whether it's reportable or not.