The doctor told Josephine that Louise's husband died. So, Josephine told Louise because of her heart condition.
Louise went upstairs to lock herself in her room because she was depressed about her husbands death.
Louise sits by the window, thinking about the different sounds she hears, and mourns her husbands death.
Louise locks the door with the window open and says she's fine and not gonna hurt herself when Josephine asks her to unlock the door.
Louise realizes that she has freedom now that her husband is dead, leaves her room and goes downstairs with Josephine
Louise dies from a heart attack because her husband comes through the door alive, and the doctors comes and says "she died from a heart filled with joy"