Every kid is different, but if you’re not able to ask the parents then a safe bet is a duplo set. Bristle blocks are also great. My kid is currently 2 1/2 so these are what I know would be hits with him and his friends.

You could also get one of the following books:

Goodnight Goodnight Construction Site
Don’t Worry Little Crab The Little Blue Truck (it’s a whole series, the Halloween one would be appropriate) Bear Snores On or any other book in that series