Preheat oven to 375 degrees. Lightly grease 10 muffin cups or line with muffin paper.
In a large bowl, mix together 1 1/2 c. flour, baking soda, baking powder and salt. In another bowl, beat together bananas, sugar, egg and applesauce. Stir the banana mixture into the flour mixture until just moistened. Spoon batter into prepared muffin cups.
In a small bowl, mix together brown sugar, 2 Tbsp. flour and cinnamon. cut in 1 Tbsp. butter until mixture resembles coarse cornmeal. Sprinkle topping over muffins.
Bake in preheated oven for 18-20 minutes or until a toothpick inserted into center of a muffin comes out clean.