I would say the answer is C. Actually am not a native english speaker but I think its the answer.
I'm pretty sure the answer is the second option.
The correct answer should be A: don't know how to deal with his mental illness
They didn't know how to handle it because it is not something that can easily be solved with cough syrup or antibiotics or anything like that.
C i’m pretty sure because the punctuation with her name.
