I didn't have a premmie but I did have a bub who stayed in hospital for an extended period. I don't think the gift is the important thing to focus on but rather the support.
I found that 99% of people didn't know what to say so instead they said nothing.
There is absolutely NILL all to do at the hospital all day everyday... don't feel like you don't want to bother them because you wont be a bother, trust me!! Also, don't assume they will want space. Space is very lonely when you think no one cares!!
Text her often and ask how she and bub is. Pay her a visit... even more then once. Your friendship will mean more then a gift. It will be remembered months and years after the fact but a present will not.
I would say the best gift of all would to just be a good friend.
All the best to them.
Bek: 33
DH: (Rob) 32
Luca Adam: Natural birth in Jan 2006, 3.6kg & BF for 22 months!!
Elliot Robert: Emerg C/S in Dec 2008, 2.8kg & BF for 29 months!!
‎Isaac Benjamin: Emerg C/S in Dec 2011, 1.9kg (32+2) & BF for 5 mths + with early help from Mothers Milk Bank!! 