@Jimme2 I would give the guest some choices about how the issue gets resolved. If the big fridge was an absolute essential to them, they should have the option to advance their checkout date and accept a refund for the remainder so that they can relocate. But if the mini-fridge and cooler option is acceptable to them, that would be he better way to go.
I like @Mark116's idea of comping a meal - or alternatively, if the guests lost some of their own food to spoilage, a gift card for the best local supermarket.