Please, be careful how you talk about your daughter's depression, to her and to others. You sound really pessimistic here, and were I depressed and hearing this about myself, I'd feel worse. When you say "I'm not sure she can anymore," there's an overwhelming sense of the depression as a permanent and crippling force. Of course you worry about how depression will affect your daughter's ability to pursue her goals and do well in school! That's completely sensible. But: Depression is treatable. Depression is a problem that many people can learn to mitigate and manage. Depression is not necessarily permanent - some people have recurring depression, in between spates of good mental health, some people have occasional episodes of depression touched off by particular stresses. It is very possible to get better.
It is a little unsurprising that a student with major social anxiety issues would have a rocky time her senior year of college, while applying to med school. The application process requires students to be charming to strangers, repeatedly, and medical school, internships and residencies are not easy on the shy. It's completely possible that what you're seeing is depression as a reaction to stress. Therapy can really help.
Skimmilk Meepy brings up a HUGE point here. i am in the same boat as you - but just with a eleven year old. her teacher tells me dont look at her grades and think she is a failure. she is an A student who is going through hard times. if you take care of the hard times then she will be back on track.
i notice with my dd she LOOKS up to me. the world can say anything to her and even though it hurts her feeling she can completely handle that. however if i say something - no matter how small, her world completely collapses. when she is in a fragile state she needs me to prop her up and believe in her that we can all come out of this in a positive manner. i have become dd's personal cheerleader.
social anxiety makes everything else going on with her complete sense. she has to interact so much more than even high school - esp. with group work.