Changing a smoke alarm battery sounds like a five-minute job. Then you find the alarm wired into the ceiling, the one over a tall stairwell, and the one that chirps in the middle of the night and nobody can reach. Size the job before you volunteer for it.
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.
Count before you climb
Walk the house and list every alarm. Note the room, the height of the ceiling, and whether the unit runs on a battery alone or is wired into the house. Some have a sealed battery built to last a long stretch, and others use a replaceable one. The label on the back, or the instructions in the box, will tell you which kind you have. Check the date printed on each unit too. Alarms have a service life set by the manufacturer, and an old one may need replacing rather than fixing.
When doing it yourself makes sense
Battery-only alarms at ground level, reached from a step stool you trust, are a reasonable job for an adult in the family. Do all of them in one visit so the whole house gets the same check. Keep a spare battery in the drawer with a note of the date you changed them. Tell Mom beforehand so the test beeps do not startle her.
When to hire it out
Hire it out if the alarms are high on a sloped or two-story ceiling, if you are not comfortable on the ladder, or if any unit is wired into the house. Replacing a hardwired alarm is an electrical job, and it is worth asking a licensed electrician to do it rather than working the wires yourself. Ask whether your local fire department offers alarm checks or help with installation before you hire anyone.
Ask the company the right questions
If you do hire, ask whether they will test each unit after changing it, whether they will write down the date and location of each alarm, and whether they will take away the old units and batteries. A company that cannot answer those three questions is not the one you want on a ladder in the house.
Put it on the list
Once you know the count, put the job on the house list with an owner and a repeat date, so it does not depend on whoever happens to notice the chirp. A calendar reminder on the same day each year is simpler than waiting for the alarm to tell you.
If you are not sure whether a job like this belongs with a local pro or a neighbor, the local help page lists where to start.