A Jew and a good parent asked a sincere question; so I don’t know why people feel the need to answer in a fresh and sarcastic manner!
Chanukah decorations are not really an answer to Xmas decorations, since that is not part of our celebration. I would let the kid look; don’t make a big deal about it. And explain that Chanukah is about lighting a menorah and singing the brachas and Maoz tzur, and eating latkes and playing with a draidel and explain the reasons behind our traditions. Decorations is not a part of Chanukah. And explain that we are living in golus with many more goyim and therefore we see their many decorations.
Have a happy Chanukah and Yiddisher nachas from your child(ren)!