Since when does a treat always mean candy? One healthy way of substituting something healthy for candy at Halloween is to forgo handing out candy altogether. (Parents of kids with braces will thank you for it!)
Instead, visit a local dollar store or bulk grocery outlet and pick up a supply of Play-doh, small containers of bubbles, plastic jewelry, glow-sticks, even vampire teeth - anything small, inexpensive and fun for kids. If it glows in the dark, even better for Halloween.
Make sure to choose a variety of toys to cover the all ages of kids who will be visiting your house, and keep the small plastic toys out of the hands of little ones to prevent choking.