First:
Smack the daylights out of the contractor!

You might look on dirtdoctor.com for the recipes & uses for Garrett Juice & The Sick Tree Treatment;
these are concoctions you make up at home for stressed plants.

I wish you the best!

First off - this forum is pretty dead. Guess no one's rejuvenating gardens, let alone a single type of plant within a garden. So if you're still here looking for responses...

Peonies are tough plants and if the work in the peony bed is finished and won't be trampled again in the spring, chances are good they'll return almost as good as new. Depending on a few unknowns, the rootstock should be okay and will have the strength to put out foliage since the rootstock was replenishing itself through the summer and up to the point of being trampled - might not get a bloom for a season, though.

I'm thinking the worst thing you could do is ferilize an already stressed plant.

The Peony Forum is equally as dead, but you could also try the Perennials Forum which still gets some traffic.