As a mother of twins the best thing you can do for your friend without a doubt will be when they are born. Just drop in when you can and give her 5 minutes to have a bath, shave her legs/armpits, let her go to the shop for half an hour just so she can be on her own. Having 2 babies is a big job, and you get some what lost in it. The other thing which my husband did for me is get her a voucher for a massage for after they are born and then maybe grab another friend and look after the babies while she goes and gets it done, also dont forget her.
You sound like a good friend and I would be lost with out my special friends, so just enquiring on what you can do to help is a GREAT start.

I wish her all the best.

Julie

PS Tell her to get all the sleep she can now, and yes I agree swaddling is the best!!!!!!!!!!!!!!!!