Answer:
Answer is C. happy
Step-by-step explanation:
Blithe means being happy but without worries. The sentence says she is reacting to her family´s misfortunes in some way she seems like she does not care but is still happy. Also, the sentence says "Nobody understood...", out of the 4 probable answers, seems like being happy about her family´s misfortunes would be the most difficult to understand from other people´s perspectives.