Not only refund vendors and pay the entertainers contracted to appear but forfeit all the money spent to rent the hall, advertising, web expenses, travel and lodging expenses, etc, etc., and any other costs incurred thus far. I would imagine a huge chunk of change has already been spent promoting and arranging for this show.
Heck, even Zumbo recanted. (He waited far too long and lost his shirt anyway, but he did eventually recant.)