Answer: Freedom
Step-by-step explanation:
Given the historical context of "The Story of an Hour," we see that the central context is freedom. During this time, women were oppressed and restricted from their rights in many contexts. When Mrs. Mallory learns that her husband is dead, she is filled with a joy that came from a security in finding out she was finally free from whatever her husband was holding her back from. However, when he walks in the door, she dies of heartbreak because she realizes once again, she is no longer free. However, the other characters believe that she died because she was so shocked and happy to see him, hence them saying she died of "a joy that kills."