"It doesn't matter who you are or what you look like as long as somebody loves you."
Just before the movie's over, the one surviving witch, who'd performed a Heel-Face Turn, finds Luke and Helga. She not only returns Luke to normal, but also happily returns his pet mice to him. There's a more subtle one when she glances at her hands and seems delighted - throughout the movie, it's been implied that she is unhappy with being a witch, so that particular scene seems to indicate she might be becoming human.
It's rather bittersweet... but the moment when the main character tells his grandmother that he's glad he won't outlive her now that he's a mouse, because he couldn't imagine being cared for by anybody else.