Fort Wilderness is a LARGE place. The Hoop Dee Doo Review is held in Pioneer Hall. This is near the waterfront, a short walk from where the boats pull in. It is not near where the Epcot buses drop you off. In either case, you're going to need to make a transfer.
Bus from Epcot to Fort Wilderness. This bus will drop you at the Outpost bus stop. This is near the entrance to Fort Wilderness and not close to Pioneer Hall (which is more than a mile away). Catch any of the internal buses (Purple-Settlement, Yellow-Settlement, or Orange-Settlement) to get to the Settlement bus stop. On any bus you'll stop at several campground sites and eventually arrive at the Settlement stop, which is near Hoop Dee Doo Review.
Monorail from Epcot to Ticket and Transportation Center. Transfer to:
(a) Express monorail to Magic Kingdom, then boat to Fort Wilderness. The boat launch for Fort Wilderness is right next to the Magic Kingdom monorail station. Your boat will stop at Wilderness Lodge, first. When it arrives at Fort Wilderness, you'll be right next to Pioneer Hall.
(b) Ferry boat to Magic Kingdom, then boat to Fort Wilderness. This is probably identical to the express monorail as far as time and walking distances. Your preference as to whether you prefer the monorail or the ferry.
(c) Resort monorail to Contemporary Resort, then boat to Fort Wilderness. CR is the last stop going in this direction. It will take a while to make the complete monorail circuit. From CR, you can take the boat to Fort Wilderness. (Note, the CR-to-FW boats stop running early. You may want to confirm what time they stop by calling CR while you're there. You should be fine for the early Hoop Dee Doo show, but maybe not for the later ones.)
Boat from Epcot to MGM. Epcot and MGM are connected by a boat. It's about a 30 minute trip with stops at several hotels along the way. The Epcot boat launch is at the International Gateway, which is near France in the World Showcase. From MGM, you can catch the Fort Wilderness bus. This bus takes you directly to the Settlement bus stop, which is near Pioneer Hall.
Bus from Epcot to Wilderness Lodge. Feel up to hoofing it? If so, there's a beautiful nature trail between the Wilderness Lodge and Fort Wilderness. This one-mile paved trail brings you out near Pioneer Hall. Or if that one mile walk seems a bit much after a full day in Epcot (no matter how beautiful the nature might be), you can catch a boat from Wilderness Lodge to Fort Wilderness. (It's actually the same boat from the Magic Kingdom, which stops at Wilderness Lodge on the way to Fort Wilderness.)
Taxi? Sorry, this is one of the very few cases where a taxi can't simplify WDW transportation. For the most part, Fort Wilderness is not open to vehicular traffic (except campers arriving and departing). A taxi can only get you as far as the Outpost bus stop. From there, you'd still need to catch a WDW bus to get to the Settlement bus stop and Pioneer Hall.
Edit: added some of the other suggests posted below