First of all, I'm sorry your mother died and I think it's wonderful that you try so hard to keep faith in your family's life and am sorry you have to work so much.
I found a clock at walmart for $15 yesterday that has photo ovals for every number and you can put photos in there. Personalization mall online has a lot of stuff you can engrave.
But personally I would get a Christmas tree ornament. If you want it to be snazzy you can get one from Macy's or bed, bath, & beyond, but otherwise you can make it yourself out of the baby's sock or something, and it will be a sentimental keepsake.
Another suggestion is to ink the baby's feet and put them on a white necktie for your husband.
I don't know your religion, but in the Catholic church we can have a mass offered for someone, or send them a spiritual bouquet. Those are ideas too. Good luck!