Preheat oven to 350 degrees.
Grease bottom and ½ inch up the sides of one 9x5x3-inch pan; set aside.
In a large bowl combine flour, baking powder, baking soda, cinnamon, salt, nutmeg.
Make a well in center of flour mixture; set aside.
In a medium bowl stir together eggs, bananas, sugars, and yogurt.
Add egg mixture all at once to flour mixture.
Stir just until moistened (batter should be lumpy).
Toss ½ cup of blueberries with 1 Tbsp. flour.
Fold blueberries and walnuts into batter.
Spoon batter into prepared pan(s).
Sprinkle an additional ¼ cup blueberries and streusel topping over batter.
Sprinkle flaked coconut over the streusel topping.
Bake for 55 to 60 minutes or until a wooden toothpick inserted near the center comes out clean. If necessary to prevent over browning, cover loosely with foil for the last 15 minutes of baking. Cool in pan(s) on a wire rack for 10 minutes.
Remove from pan.
Cool completely on rack.
Wrap and store overnight before slicing.