Help stop smoking.

Any idea how to convince a mentally handicapped person to stop smoking? I've tried my whole life to convince my mother but she just doesn't understand. She has COPD & was recently hospitalized due to pneumonia from smoking. My mother has been cut down to 2 cigarettes a day for quite awhile. After being released from the hospital she was given an ecig to replace her cigarettes. She was fine for awhile but  started to become horrible, Being rude & ultra bitchy to my great aunt (her guardian) & her doctors. My aunt is old & it's harder for her to handle my mother now days so she gave in & gave her, her cigarettes back. No one really knows what to do.... Giving my mother her cigarettes back is not what my aunt wanted to do because it just makes her feel like she's making the problem worse. My mothers smoking & copd will be the death of her no doubt. We just want to help her but she won't let us. How do we help her understand that it's going to kill her & that she needs to stop?