Demons hide in your food? I wouldn’t worry except if the food came in contact with a certain “Mexican” warlock in Kentucky. Make the Sign of the Cross and say Catholic blessing before and after eating.
As to whether you take your child Trick or Treating, it depends very much upon where you live. If you live in a small town, usually there’s no problem. If suburbs, go in your immediate neighborhood. In an urban area, it’s more problematic. In some cities, businesses give out candy to children in costume and accompanied by an adult, or go door to door in your apartment building. If you know someone to be suspect, obviously, skip that home. Most people who participate leave their porch or front lights on, or even stand in the doorway to greet the children.
I’m too remote for anyone to come Trick or Treating. Nobody drives five miles down a gravel road to visit two houses. At any rate, I have no light visible from outside and it’s overcast and very dark tonight.
Catholics should reclaim All Hallows’ Eve from the superstitious Protestants who don’t believe in Purgatory, don’t pray for the souls there, and teach their children to be afraid on Halloween as if Our Lord hands over His protection to the devil. I’ve even heard Protestant adults say that Halloween is Satan’s birthday! When I was teaching there were Protestants who kept their children out of school and skipped their work for fear of witches or demons. (And they accuse Catholics of being superstitious!)