I lost my son 2 years ago on Aug 11. He lived only 5 hours. All I can suggest is that whenever you choose to give will be received with bitter sweet appreciation.
I have all the little cards and gifts in a box. I can't look at them. The one time I tried to look, I totally lost it. But I know that someday I will look in that box and I will be ever grateful for all the kindnesses that family, friends and strangers gave my family and me. Those are part of the memories I will have of him.
Honestly, one of the kindest gifts I received was from a very close friend. She offered to put away the baby room when I was ready. She returned things to the store that I didn't want to keep. She handled everything and I didn't have to explain to any part of my loss to the store associate.
Another thing you might do is knit some hats or blankets and donate them to the hospital where the baby was born in his or her honor. I started a charity and donate items on my son's birthday. This is a way to put a "positive" to the memory of the lost baby. You don't have to show the FOs to your friend (it will be too difficult for her to see), but tell her about it. Or better yet, put it in a card.
The best thing you can do is just be there for her if she or her family needs something. I can't even begin to tell you how long this will last. I still deal with my loss everyday.