I'm so sorry about your loss. How lovely that you and your daughter are planning something special for the holiday.

There are lots of bike shops in Manhattan. Here are a few that I know. All of these are easy to reach by subway.

http://bicyclehabitat.com/

http://www.paragonsports.com/
Large store with a bike section that's worth visiting. Lots of outdoor
clothing, too.

http://www.sidsbikes.com/

http://www.adelineadeline.com/
Downtown in Tribeca. Very, very upscale but fun. They have Yakkay helmets.

http://www.chelseabicycles.net/
Where I get repairs done. Small, crowded and funky, but nice people.

http://outlier.cc/
Outlier has a showroom in Brooklyn. I haven't been there, but it might be interesting if you are in Brooklyn.

Hope you have a great trip!