Banana Crumb Muffins

1 1/2 cups flour 
1 tsp baking soda 
1 tsp baking powder 
1/2 tsp salt 
1/2 tsp nutmeg 
3/4 tsp cinnamon 
4 ripe bananas, mashed 
1/2 cup sugar 
1/4 cup brown sugar 
1/3 cup melted butter 
1 egg, lightly beaten 
1 tsp vanilla 
Crumb topping: 
1/3 cup brown sugar 
2 tbsp flour 
1/8 tsp cinnamon 
1 tbsp butter

1. Preheat oven to 375F 
2. Whisk together flour, baking soda, baking powder, salt, nutmeg and cinnamon. 
3. In a separate bowl, beat bananas, sugars, egg and butter. Fold into the flour mixture. Pour into lightly greased muffin tin. 
4. For crumb topping: Mix together brown sugar, flour, cinnamon and butter until it resembles coarse meal. Sprinkle over top of muffins. 
5. Bake 18-20 minutes.