To make the muffins, preheat the oven to 400 degrees.
Stir together the flour, sugar, salt, cinnamon, and baking soda in a large bowl.
In a small bowl, whisk together the yogurt, buttermilk, vanilla, and egg until combined.
Add the wet ingredients to the dry and stir until just combined. Fold in the berries.
Fill greased or lined muffin cups 2/3 of the way full.
To make the streusel topping, combine the flour, brown sugar, oats, and cinnamon in a small bowl. Cut in butter until the mixture is crumbly. Sprinkle over the tops of each muffin.
Bake for 20-25 minutes or until a tester comes out clean.