Preheat oven to 350°F.
Line 11 cavities of a regular size muffin pan with paper liner.
In a medium bowl, add whole wheat flour, baking soda, baking powder, salt and mix thoroughly with a whisk.
Peel the bananas and mash them with a potato masher in another medium bowl.
Add the light brown sugar, egg, yogurt, coconut oil and vanilla extract to the mashed banana and mix with a whisk until smooth.
Pour the whole wheat flour mixture in with the liquid mixture and mix until just combined.
Fold in 1 cup of blueberry.
Divide batter equally into the previously prepared muffin pan.
Top the batter with the rest of the blueberry, and sprinkle with 1 tablespoon of streusel.
Bake for 20 minutes until a toothpick inserted in the middle comes out clean.
Remove from oven and let cool on a wire rack for 5-10 minutes.
Flip muffins over to get them out of the muffin pan and onto a dish towel. Let them cool on their sides on the towel.