J.C.
It's hard to say what she'll need but there's probably not a whole lot you can do aside from being there. Nurses will be in and out and she'll (probably) want someone to stay there with her and be able to run for things or communicate with nurses and the doctor or midwife.
Consider finding a doula's list of things to bring to a birthing room. No matter what came up during my labor and delivery, my doula had something for it. Hot pack for my back, kneeling pads for kneeling next to the birthing tub, I can't remember what else but there must be a list out there of handy things to have.
Something I liked during labor was photos of babies, (mine were cut out of magazines.) It was inspriring and reminded me of what I had to look forward to.