It all depends why a person is taking narcotic pain killers. If they are truly in severe, chronic pain, it would be cruel to demand that they stop. If they are just taking the drugs to get high, that is another situation altogether. The problem is that it can be difficult to tell the difference.
People who take narcotics for real pain do not get "high"; they do not take more at one time than prescribed. The drugs make them more functional, rather than less functional. They fill and use their medication as per the doctor's instructions.
If your mother is able to wean off of narcotics and is not in severe pain, she is not taking them for the reason they are prescribed. Still, the addictive behavior must be dealt with, on a long term basis.
Good medications for severe, chronic pain are Methadone and Suboxone. Not so much of a "high" feeling from these. They are also both used for drug withdrawal and addiction to stop the intense cravings for narcotics. These medications have their own withdrawal effects when discontinued.
I used to work at a pain clinic and I saw a lot of people there for the drugs, but I also saw a lot who were there because of intractable pain. It is difficult for the doctors to tell the difference. The guidelines I mentioned above are what they use to determine whether to prescribe narcotics. Is your mother using drugs for pain or to withdraw from life?
I wish you and your mother the best as you try to figure out what helps. Drug addiction is a sickness in itself and needs a lot of intense, long term treatment. Unfortunately, our society tends to demonize people rather than provide the long term care that is needed.