I did a photo album for my friend and her hubby. From the front to middle i did her life and the back page to the middle i did his life. In the middle they met with a photo of both of them. it took me FOREVER to do it but they absolutely cried like babies. Both of their parents helped me.
It depends on how well you know her. my friend & i were mates for 18 yrs before this so i knew everything.
If not, something like a joint day out together for them is nice. Something personal