I think you need to spend more time on the requirements before you start the design. Some questions I would ask:

How far is your commute?
How hilly is your ride?
What surfaces will you ride on?
Will you ride in the dark?
How much will you carrry?
Do you have secure storage?
Will you ride in snow/ice?
Will you use the bike for other than commuting (e.g. charity rides like MS 150)?
What riding position do you prefer (upright vs crouched)?
What is your mechanical ability?

I'm sure there are more questions you could ask.

I also think you need to be careful with this project. It could end badly in many ways:

You purchase parts and she doesn't pay you back.
You overlook something in the assembly and something gets damaged (or worse she gets hurt). Who is liable?
She just doesn't like the bike, and your Mom's friendship sours.
You wind up not having time to finish the project.

Paul