Here are some links to lists and articles that might help make this holiday season a little easier to navigate. Of course, if you're ever in doubt, it's better to err on the side of safety, and you can also contact the manufacturer's customer service department to find out if your candy is safe.
Gluten Free Candy
Peanut and Tree Nut Free Candy
Allergy Free Candy - All candy is free of the top 8 allergens - wheat, milk, soy, eggs, peanuts, tree nuts, fish or shellfish.
Allergy Free Halloween Candy Round-Up