Preheat oven to 350º degrees. Ovens may vary with temperature.
Spray muffin pan with a non-stick spray, or use paper liners.
Chop the dates into small pieces, and set aside to add at the end.
In a medium bowl combine flour, bran, baking powder, baking soda, and salt. Set aside. Using a fork mix the dry mixture so it combines evenly.
In a large mixing bowl add the bananas and mash them, leaving a few chunky pieces of the banana. Then add the brown sugar, eggs, and melted butter. Mix on a low-med speed until well combined.
Now, add the flour mixture into the mixing bowl with the wet ingredients on low to medium speed; adding a small amount at a time until smooth and well mixed. Fold in the dates, and walnut if including in the recipe.
Fill the muffins 3/4 of the way, and bake 25-30 minutes. They will be done when edges and top are slightly browned.