Your shot has many nice features, including the shapes of the background walls. I think Mary's B&W treatment added some mystery, whereas this shot is about straightforward fun.
Congrats on the nice placing! it's really interesting how different the mood of yours is - it's warm and hopeful. It's funny - the contrast in the expressions between the fore-child and the background ones makes this very complex and mysterious despite the brightness. It's as if all three are reacting very differently to the same sound. Very thought-provoking!
I like how Mary has the kids going one way, and you have the other view. Also funny that she went with B&W and you went with color. You two should work together. The color choice is perfect here to enhance the sense of fun and energy. Adorable moment. Congrats on 15th place!
Good triangular composition. Funny to see this and a nearly identical b&w version in the same challenge -- I'm curious to find out who the two photographers are!