In a large bowl, mix together 1 ½ cups flour, baking soda, baking powder and salt. In another bowl, beat together bananas, zucchini, sugar, egg and melted butter. Stir the banana/zucchini mixture into the flour mixture just until moistened. Spoon batter into prepared loaf pan.

In a small bowl, mix together brown sugar, 2 tablespoons flour and cinnamon. Cut in 1 tablespoon butter until mixture resembles a coarse crumble. Sprinkle topping over bread.

Bake for 50-60 minutes or until an inserted toothpick come out clean. Allow bread to cool before removing from the baking dish.