I'm not a nurse, but I do have some ideas for you..
Maybe a Stethoscope. Like a Littman one, those are expensive high quality and a BP cuff, both in her favorite color. You can't go wrong with giving a Littman scope.
Or a gift card to a really good scrub store..
A gift card to a day spa
Or like a charm braceltt with all "nurse" type charms..
Hmm thats all I have for now, if I think of more I will let you know!!
http://www.nursesdirect.com/nurse/ That is a good website to look at and get some ideas!!