I'm so sorry for your loss (and the struggles you must have endured during the few months preceding). I think taking a special mother-daughter trip for the holidays is a wonderful idea.

I've only been to NYC once as an adult, and it was very brief and in the summer so I unfortunately don't have many ideas to offer. I would say if you tire of shopping (impossible!? ) spend some time in Central Park--I was amazed at how when I was wandering through it, I forgot I was right in the middle of the big city--but I'm not sure what that's like in the winter (or how fond you are of being out in the cold. I love it, personally, but I know it's not for all!

Here's hoping you find plenty of great places to shop and sightsee, and that the exchange rate stays firmly in your favor!