From Muppet Wiki

Bear's Egg Hunt is a lift-the-flap Bear in the Big Blue House book. In this story, Bear and the kids of the Big Blue House decorate eggs together and then Bear hides them throughout the general area of the house. The kids all have fun hunting for them, but Treelo becomes disappointed when he can't seem to find any at all. Then, he makes a surprising discovery.

This book combines photos of the characters from the show with original illustrations. It also features a duckling and his mother, but they are apparently not related directly to Harry or his Mom.