I would probably have wanted the morphine to reduce the pain that I may have experienced as death drew near. Of course, the big difference is that I would never have allowed myself to be addicted to morphine in the first place, only wanting it at the end to relieve my pain. In Mrs. Dubose's case, she had been a morphine addict for a long time; she probably realized that the drug is what significantly caused her to be so angry and disillusioned with the people around her. She may have also realized that it affected her thinking and decision-making, so by ridding herself of the addiction, she was able to clearly live out her remaining days (or hours). We don't know exactly when or why Mrs. Dubose became addicted in the first place (it was prescribed originally by a doctor as a pain reliever), but it must have been a cause of shame for her since she made the courageous decision to kick the habit before she died. It was an interesting decision, to spend her last days in agony instead of pain-free, and not one that most people would make; but Mrs. Dubose was not your typical Maycomb woman, and her decision to "leave this world beholden to nothing and nobody" showed an independent streak that few others in the novel exhibited.