All you can do is take a wait-and-see approach.  If it was cold enough to damage needles and not twigs, the bushes may push out some new growth in May or early June.  If it got cold enough that the cell walls exploded in the twigs, the bushes are dead.  But there is no way of knowing... wait and see.  If it is the middle of June and there is nothing except a few forlorn needles remaining, they are formerly living landscaping.  It indicates that there is enough damage that there is no going back.  They will never recover.

Your part in this is to make sure that if it is dry, you keep the shrubs watered so the soil is moist.  You do not want soggy or saturated soil...damp is good enough. Do not fertilize because that will kill them- guaranteed.  If they are not looking pretty perky in about six weeks, they never will.

Right now, it is up to the shrubs to see whether they can respond or not.  You can't fix exploded cell walls if they have them, it is up to a higher power than us.

Thank you so very much. Your comments were very helpful. We'll just wait and see and hope for the best.

It's the simplest approach.  If the shrubs can respond, they will.  You are just making sure they have enough moisture to get to work, if they can.  You make opportunities but you can't make the shrubs take them.