Steve,
Assuming they were in business in 1921, any of those three look like good candidates. Since there is just the one sentence, there's probably no way to determine which. I'd like to think it was Norris's 'cause that looks pretty cool.
Jim,
I imagine Granddad was pressing every pedal in reach and probably squeezing the steering wheel pretty good, too. There were no wheel brakes and the single brake band was indeed in the transmission. Granny does say band
s though I don't think we can count on her for technical precision. That could have been a figure of speech or it may have been common practice to replace all three bands (low, reverse, brake) when replacing any. I'm guessing that's what they did. I have the Model T Instruction Book (owner's manual) and it not only explains how to drive the car but how to maintain and practically rebuild it, too. I did some rambling about it
here.
EDIT: That isn't quite right. There was a brake on the rear axle that was activated by the hand level. It is called an emergency brake or a parking brake but I have the impression it was routinely used in stopping the car not just holding it.