Preheat the oven to 350 degrees and spray or line two 12-tin muffin pans.
In a large bowl, combine the grated zucchini and carrots, banana, applesauce, eggs, sugar, oil, vanilla, and lemon juice. Mix well using a fork.
In a medium bowl, combine the cinnamon, nutmeg, flour, salt, baking powder, and baking soda. Sift or mix well.
Slowly pour the dry ingredients into the wet ingredients and mix well.
Evenly pour the batter into the muffin pans, filling them about 2/3 of the way.
Bake for 20 minutes or until an inserted toothpick comes out clean. Cool muffins before serving for best results.