In some ways, our narrator needs his grandma more now than when he was a boy. As we see toward the end, she has to rig up some strange gadgets to help him get around, and she even has to construct a mouse toothbrush for him. He's not kidding when he says he'll always need her to look after him. As a boy, he would have grown into a man and not needed her anymore. As a mouse, he'll always need her help.