Hi there, Jennifer!
Well that sounds like an awesome vacation. It can be so awesome to visit the
Disney Vacation Club beach resorts during the fall. Typically, the weather is a little bit cooler, the resorts are a little bit quieter, and there's still so much to do. I hope you enjoy your trip.
Both
Disney's Hilton Head Island Resort and
Disney's Vero Beach Resort have, in years past, done something for Halloween itself. Between the two resorts, there was trick or treating, crafts and activities for kids, and even a special Halloween movie in the evening (Hocus Pocus played at the Beach House in Hilton Head last year). You may hear Halloween music at the resorts, and one year, because the weather was chilly, complimentary hot cocoa was given to guests at Disney's Hilton Head Island resort during trick or treating.
When you check in at your resort, be sure to ask at the front desk for a schedule of activities. I would say you'll find most of the Halloween fun when you arrive at Disney's Vero Beach Resort, so definitely check there for the fun Halloween plans for the day.
Wishing you a spooktacular time, Jennifer!
Anna