Question: 

"Almost every time I visit my mother, it seems that she is missing most of her pain medication.  Mom is not a great historian, so it is difficult for me to figure out if she is taking a lot or someone is taking it.  I only ever see her take one pill in the morning,  so her 30-day supply should not run out every week.  What I do know is that my nephew has had a history of drug use, and he shovels her driveway. He is alone with her in the house. How do I go about figuring out if we have a problem here?"

Answer:

It sounds like you are the one refilling her medications, so it makes sense that any unusual shortage would be noticed by you.  And since your mother is unable to answer your questions, you will need to do a bit of sleuthing to figure this out.

Let's just assume that someone is taking your mother's pain medication. If it is your nephew, it is unlikely that a confrontation will result in an admission of guilt.  That would be way too simple.  People who steal drugs are not usually inclined to confess, so let us discuss a possible Plan B. 

If your mother is capable of managing a key, I would recommend obtaining a lock box for the medication and having your mother store the key in her sock.  She should avoid wearing the key around her neck or wrist, so that it is never visible.  People who steal drugs are crafty.  Remember, they are likely addicted, and you do not want to place your mother at any risk.  Do not be surprised if the thief tries to locate the key for the most interesting of reasons.  Your mother needs to be cognitively strong to manage the key, so think through this option.

A more expensive option is installing a surveillance camera that also saves recordings. Thieves are devious, so this would need to be done without anyone's knowledge except your mother and you. 

I know of some very smart families who have set up a sting.  You could count the medications and circle back immediately after the nephew's visit.  He will say that he did not take the pills, but you will know.  This may be the easiest of solutions if you have the time.

How you decide to handle the situation will depend on specifics and your resources. You are doing the right thing by protecting your mother and managing her medication. I applaud you for your diligence. It is important that we all have somebody who looks out for us, regardless of our age.