Start by walking the route the way she walks it at night. Sit on the edge of the bed, stand up, take the first step, and notice the moment her hand reaches for the wall. That spot, not the spot you guessed on the floor plan, is where the rail belongs. Most of the six stops do not need a rail, so pick only the one or two places where she actually reaches.
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Before you buy anything
Measure the height at her hand, not at yours. Have her stand relaxed beside the wall with her arm down, then ask her to reach out as if she were catching herself. Mark that height with painter's tape. Write the number down before you shop.
Find the studs. Use a stud finder, then confirm the first stud with a small test hole in a spot the rail will cover. If the wall turns out to be hollow with no framing behind it, stop and read the rail package again, because the rating on the box usually applies only to mounting into framing. Plaster and drywall over framing need different screws than a bare hollow wall, so do not guess.
Read the package before you buy. Look for the load rating, the screw length the maker specifies, and whether the maker requires mounting into a stud. Keep the paper with the rail. Decide who will drill: you, a handyman, or a contractor. If someone else drills, ask them what they will check before they leave, and ask them to show you the finished screws.
The Saturday, in order
First, scan the wall with the stud finder set to detect live wires and pipes, and mark anything it finds so you do not drill into it. Second, mark the stud center at her hand height with a level line across the tape. Third, drill pilot holes into the stud itself, not beside it. Fourth, mount the flange with the screws the package specifies, not shorter or thinner ones from the junk drawer. Fifth, test it: push on the rail hard from the side she will pull from, then check for any movement at the screws or the wall.
Only when the rail is firm should you ask her to take her weight on it. Stand beside her while she does, and keep your hands ready. Do this test only if she is steady on her feet and her doctor has said standing and walking are safe for her. If she gets dizzy when she stands, do not test the rail on her yet. Call her doctor first and ask whether a standing or balance check is needed before she uses the rail on the night route.
What to write down
Write the stop number, the height from the floor, the wall type, and the stud locations you found. Record the screw and anchor type used and the load rating from the package. Write the name of the person who drilled, and whether it was you, a handyman, or a contractor. Note the test you did and who was present when she tried the rail. Then add a monthly check to the same page: look for loose screws, cracks in the wall around the flange, and any movement when someone pulls on it. Put the page in the same folder as the package and the receipt.
For how the steps in this guide are checked against public sources, see How we write this desk, and the list of sources behind the general safety points is on the Sources page.