I have several kinds of hostas and the leaves are definately damaged after last night's cold. I think that after the cold passes, they will continue to put up new leaves and be just fine. Hosta and Daylillies both are very tolerant of these late freezes. I have never lost any to late cold, regardless of leaf damage. I hope yours pull thru and return to good health. They are amazingly hardy plants so there is every reason to think they will!
If you don't have too many, you can cover with leaves, mulch up high around them or even put cardboard boxes over them. This won't protect against actual freeze, it's used more to protect against frost, but it should help some. Also go out and water them well if you can. A well-watered plant is less likely to suffer damage than a dehydrated one.
~Christine

This is my leap (third) year on many of my plants & here this freeze came along. I covered peonies that had buds, an english rose, & my crinum Jeff gave me a couple years ago :-) & some other small perennials.

My poor clematis had at least a thousand buds & was going to be gorgeous.....WAHHHH!!!

I wonder if this will get the peaches around here.