I purchased some large wooden Mask in Hawaii. What is the best way to hang them. no hardware was included.?

I collect all kinds of masks and hang them as art on my mask collection wall. When the masks dont have holes in the sides and ribbons through them, I use the eye holes to feed fishing wire through and then drill a hole in the wall, insert a scew and wind the fishing wire around that. Your masks sound large, so use fishing wire that is strong, I use 10 pound test but you might need something that can support more weight than that. Also, you should probably use an anchor molly if you are screwing directly into drywall and not into a stud for added strength.

Don't add hardware. Buy a hanging bracket or mini-shelf. Most masks like that should be on stands, not hanging by nails.