Preheat oven to 350°F. Lightly grease 12 muffin cups or loaf pan, or line with muffin papers.

In a large bowl, sift together 1 1/2 cups flour, baking soda, baking powder and salt. In another bowl, beat together bananas, sugar, applesauce and melted margarine. Stir the banana mixture into the flour mixture just until moistened. Spoon batter into prepared muffin cups.

Optional Crumb Topping: In a small bowl, mix together brown sugar, 2 tablespoons flour and cinnamon. Cut in 1 tablespoon margarine. Sprinkle topping over muffins.

Bake in preheated oven for 18 to 20 minutes (15 minutes for minis, 1hr 10 minutes for loaf), until a toothpick inserted into center of a muffin comes out clean.