Here are a few quick ideas:
1) Instead of pumpkin carving, let them make pumpkins with paper and glue and carve an actual one yourself. Then stuff them with pumpkin pie.
2) Look for PDF masks to print and let the kids colour them.
3) Find or make wordsearches about Hallowe'en with levels of difficulty to match their ability. (e.g. boo/cat/witch, halloween/pumpkin/nightmare) There are plenty of them to be found.
4) Find a short story that kids can read or participate in telling or acting, preferably with printable images. Or, give the kids a set of vocabulary and a madlib to fill in.
5) Make a skeleton piñata out of newspapers, and fill it with candy.
6) Play a variation on a cakewalk game or musical chairs with themes or words attached instead of numbers.