HI,
I would go look for restaurants in the McHenry area that received good reviews. It may not be many, but it is a good place to start.
Captain Porky's on 41 does catering or at least you can pick it up to go. There is a constant flow of people picking up food for parties at his place.
If BBQ is your fancy, Big Ed's in North Chicago could take care of you.
My favorite caterer is Appetizers by Chef Paul in Gurnee. He is a favorite because I know him and know his philosophy: he makes as much as possible from scratch.
I used to have a favorite BBQ very close to McHenry. Unfortunately Big O's has been gone a few years. I lived for his Sloppy O's, which I just realized was a re-use of burnt ends. No wonder I loved it.
When it comes to McHenry proper, I just don't know enough.
Regards,