Why and how does Mrs. Dubose make an attempt to change her behavior?
According to Atticus in chapter 11, Mrs. Dubose had a morphine addiction that she was trying to change before she died. She contacted Atticus to draw up her will and had explained the following to him:
"She said she was going to leave this world beholden to nothing and nobody. . . it's all right to take anything to make it easier, but it wasn't all right for her. She said she meant to break herself of it before she died, and that's what she did" (111).
For about a month before she died, Jem went over to read to Mrs. Dubose as penance for destroying her camellia's after she called Atticus a "ni***r lover." She had an alarm clock set during the time he would read to her which would clock his reading time as well as her own suffering without the morphine. Jem didn't know it at the time, but Mrs. Dubose extended the alarm's length of time each day in order to kick her habit and help to wean herself off of the medication. No wonder the reading time seemed to get longer each time!
Atticus says that Mrs. Dubose is very courageous for tackling a drug addiction at the end of her life like she did. She very well could have justified taking the morphine because she was dying anyway; but she didn't. She wanted to leave her life free from the morphine and Jem actually helped her to achieve her goal.