From the 6th General Hospital unit history.
"Early in 1944, the unit was reassigned to the newly organized Peninsular Base Section (PBS) in Italy."
I have reason to believe ARC or A.R.C. stood for American Red Cross. It appears these were volunteers who served in military units but were not 'official' like the WACS or WAVES.
Here is a brief description of the crash:
https://aviation-safety.net/database...?id=19450202-3
Here is a site that may have more information about her:
https://www.ancestry.com/search/coll...nursefilesww1/