Congrats!! I have boy/girl twins; their dad called it his instant family.
Tell her to take the easy way and not listen to too much advice from singletons
Some of the things I did that really worked out great:
I both nursed and gave bottles. There's no such thing as 'nipple confusion'. Stick something in a baby's mouth and they think 'food' and will eat.
Keep a cooler of bottles for night and early morning feedings in the babies' room or yours. Saves time having to prepare anything when they awake. ( I made formula by the pitcher two-three times a day)
When one wakes up, wake the other. If bottle feeding at night, fill the nearest sink with hot water, drop the bottles in, then scoop up the babies and bring them into bed, change them. By the time they're ready, the bottles are too. (bottles don't need to be heated or sterilized-just need to take any hard chill off them so the babies don't get a 'cold shock' in their mouths)
It's ok to prop bottles.
Take advantage of the doctor's generosity. Mine would give me medications, formula, etc. Never say no to that stuff!
If anyone asks what can they do-tell'em buy diapers on their way over to visit!!
One of the things I did (that didn't set too well with some family members, but oh well) is I insisted NO visitors my first week home. No grandmothers, neighbors, nothing. A C-section is major surgery and there's two babies demanding my time. The time alone as a family is important those first few days-the last thing she needs is to be entertaining people who came to ooh and ahh and give 'advice' she won't use.
Enjoy!! Twins are the coolest and I don't see how anyone has just one at a time-that's so boring!!
Oh!! One final thing I did that is still treasured: Every day for at least 10 minutes, I videotaped the babies. I did it for two years. There's going to be small things they do that you and she won't remember, trust me on that one! I've caught my son at 16 months playing his dad's Nintendo, my daughter with chocolate pudding all over her face, the two of them having a 'twinglish' conversation....it's amazing.