Howler, I am so sorry to hear what your DD has gone through.

I like the safety net idea.

I have seen the following accommodations for college students:
--reduced or eliminated class attendance requirement
--testing in separate room/ small group
--testing in smaller chunks (e.g. exam in three short bursts instead of a one hour sitting)
--flexible deadlines (though of course it all has to be done by term's end)

You could also consider whether any of these would help:
--testing in a particular environment (removed from places that are triggering)
--no-penalty resubmit/retake option on some or all assignments or tests

So much of PTSD appears to be environmental/situational: would she be better off finishing her degree at another school? (I know, that is not a trivial matter. Just asking.)

I am betting you are getting no advice because no one there knows what to do. I hope my guesses are useful.