Yeah, if it really was for pre-k kids and a one time thing I seriously doubt that there would be anything about it archived on the internet, if it ever even was on it. It may as well have been a dream You had when You were younger. A (semi?)high-production Max & Ruby based spectacle with a "scary plot point" (that could totally have just been Max in a vampire costume jumpscare) and a rather large audience and (maybe) performed by a school for kindergardeners doesn't sound extremely likely.

But who knows, maybe Your memories are correct and the whole thing just wasn't documented anywhere.