It is hard to say for sure if they will come back in the spring because some types of passiflora are more cold tolerant than others. If the stems are still green inside they are still alive. I would just keep watching them and watering minimally. As long as you can keep them warm and in the light and frost doesn't touch them, (if they are frost-sensitive types) I would think your chances are excellent that they will return in the spring.
Just my .02 cents
~SJN