((((Socci)))))
your friend is really lucky to have such a thoughtful friend!
The main gift you can present her with is your time and your shoulder to cry on. Someone who listens, someone she can trust not to judge her for what she is feeling and also someone who can give reassurance that these feelings are normal.
One thing best not to say is: Ah well, doesn't matter, both you and the Baby are fine! Because it makes you feel inadequat for any negative feelings you may harbour. Not disputing the fact that of course it is important that you both are physically alright....it's just well, the emotional side is also so important.
Someone mentioned already to tell her about the Birthtrauma association and I can only 2. that they are fantastic.
As for a gift you can buy or make...if she likes to read, that might be something...a nice novel, or whatever she enjoys. Maybe a aroma therapy kit and some Bach's Rescue Remedy could also be good...(I swear that Bach Flower remedy truely helped me through some low and stressful times and it is alright even if you breastfeed, so will be suitable no matter how your friend feeds her lil one)!
Chocolate, if she has a sweet tooth
Sorry, I can only really think of the obvious here, I think!