How long does it take for a banana to brown while it's in the freezer?!
Answers:
A day
Bananas in the freezer will never brown, and once frozen, I don't think taking them out will restart the browning process.
BUt, you can make banana bread out of most bananas because the baking process should get them to the right sweetness along with whatever sweetener you use.
Note that is is easier to cut bananas when they are frozen, but it may not be easy to peel frozen bananas.
Next time, try letting them ripen on the counter and you can compare that to what you make this time. You may find you like the less ripe banana bread better.
If you really want them to ripen but not freeze just put them in a brown paper bag. The hormone that causes fruit to ripen will be trapped in the bag and cause the fruit to ripen much faster.
To ripen them leave them in the sun. It would take a day or two depending upon how ripe they were when you bought them.
Freezing will make the skins go black, but will stop the ripening process.