The correct answer is option A. The best analysis of the passage's symbolism is that the light represents Granny Weatherall's life. Written by Katherine Ann Porter in 1930, the play tells the story of a woman, Granny Weatherall, who is in denial of her character and life story, and who refuses to believe that her health is deteriorating. Granny also is fixated with a man that left her at the altar, although she refuses to accept so.
Granny starts to perceive a blue light, the one that is coming from Cornelia's lamp. But what this blue light represents is the life of Granny, as it starts to fade. At the end of the play, Granny begins to imagine how the pitch darkness of death is beginning to surround the blue light, her life, and consume it.