A handrail looks like a simple project, and sometimes it is. The question to settle first is not which bracket to buy but who will do the work and who will check it. Those two answers decide whether this is a weekend job or a visit from a carpenter.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Sort the wall first
Find out what the wall is made of. Solid framing behind drywall is the most forgiving situation, because the bracket can be fastened into wood that will hold. Plaster over lath, hollow walls, and masonry each need different fasteners. The bracket has to anchor into structural framing, not only into the surface finish. If you cannot locate the framing or you are not sure what the wall is, the job is leaning toward a trade.
Count the tools and the time
You will need a stud finder, a drill, a level, and the right anchors for the wall type. Check whether the rail is sold as a kit with the correct length, returns at the ends, and brackets matched to the spacing on your stairs. Plan a full day, not an hour, because measuring twice is where most of the time goes.
Decide who tests it
A rail that is installed correctly should hold a firm load when pulled in more than one direction, at the top and at the bottom. That test needs a second person on site. Plan to retest after a few weeks, since fasteners can settle. If no one can be at the house to test it, the job belongs with someone who will.
Compare the two paths
Doing it yourself costs you a weekend and leaves the result on your own judgment. Hiring it out costs a carpenter's visit and gives you a written estimate. Ask the carpenter to name the bracket type, the fastener, any blocking added inside the wall, and how the old rail will be removed if one is in place. Ask whether they will anchor into framing, whether they will demonstrate a pull test before they leave, and what the installation warranty covers.
Check the fit for her
Height, grip width, and whether the rail continues past the top and bottom steps matter as much as the bracket. Ask her to try the rail at the height you plan, or ask a therapist to advise on the right height and grip size.
What to do tonight
Photograph the wall at the top and bottom of the stairs, measure the run, and note whether the stairs are open on one side. Then decide. If you have found solid framing and a helper is available, the job can be yours. If not, start looking for a local carpenter.
What to leave with the doctor
Ask whether the planned height, position, and grip suit her, and whether she needs a stair assessment before anything is installed. For help finding a local helper or carpenter in St. Louis, the Local Help for a St. Louis Parent page is the place to start.