If the leaves got frost damage, there's a good chance that the bulb was damaged too.

You will know of the bulbs are damaged by whether or not they get mushy. How cold was it and for how long? Where do you live?

Since the leaves are gone and if you are apt to have another freeze, I'd be inclined to bring them into a place that's a little warmer but not necessarily I'm the house. If this is the bulb's natural winter it should be getting some rest anyway. Any chance that the leaves just turned yellow and fell off as the result of he change on seasons?

If there is bulb damage you'll need to start peeling layers until you get to one that is solid. It's a pretty big shock to the bulb and you'll need to keep an eye on them.

Good luck!
Kristi