Mix flour, baking powder, and baking soda in a bowl.
In a mixer beat bananas. Then add sugar, oil, egg and vanilla.
Alternate adding dry ingredients and milk into the banana mixture. Beat until just combined, do not over mix.
Fold in blueberries. And scoop into lined muffin tin.
For the streusel topping melt butter, then stir in sugars. Stir in flour until it forms little pea sized clumps. Sprinkle the topping over the muffins.