Unfortunately, I don’t have much time to play and test this myself, so if anyone knows the answer, I’d really appreciate it 
Watching a YouTube video, I noticed that if you’re doing trick-or-treating with a child, no NPC gives you candy. They all say no, poor creatures
Can you confirm this? Have you tried putting candy in the NPC’s inventory to see if they then say yes?!
Wait what?
I haven’t been able to test this yet. Those poor children LOL Imagine seeing the rest of the neighborhood getting bucket loads of candy but everyone rejects you…
I’ll let you know, damn, how can you say no to these little faces?!
i’ve had the same issue. sent my child zoi to ask like 6 different people for candy, none worked so i gave up.
Probably the NPCs haven’t been configured for that yet. You could try using the NPCs placed by the game in houses (like the Williams) by maybe putting the candies in their inventory, or perhaps placing the candy bucket in the house—maybe it works 
I’m updating you, we have great news: NPCs give out candy if children wear the costumes downloaded from the official Canvas page. In fact, when they wear them there’s this mood state:

“This is the Halloween costume and adults will feel inclined to give out candy”
I tried it and no one says no anymore!
Looks like this is it! Someone flags it as solution 
[That’s right, this is wonderful news here] 