There is a trick or treat location set up in Columbia, but it is not open for dinner during MNSSHP. The lines goes in one door and out another door. I think Pecos Bill and Cosmic Ray's are open during MNSSHP.
Last year, we were at MNSSHP and there was a character greet area in CHH. We were bummed because we really wanted to eat there. Not sure if it's still this way, but Pinnochio's Village Haus was open for dinner (and dead inside). It was a nice place to hide out from the crowds and the rain.