A chimney sweep is a yearly or less frequent job, depending on how much the fireplace gets used, and the visit goes better when the room is ready before the crew arrives. Dad will want to supervise from the armchair. Let him, but plan for him to be somewhere else while the soot comes down.
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.
Step one: decide whether the fireplace is still in use
Ask him straight out. Look at the firebox for old ash, check whether the damper opens and closes, and look above the opening for any soot or staining. Tell the company whether the fireplace is used regularly or has been closed off, because a fireplace that burns every week needs a different look than one that has sat sealed for years.
Step two: book the visit and confirm what it covers
When you call, ask whether the price includes cleaning the flue and the smoke chamber, checking the cap and crown on the roof, and writing up what they found. Ask whether they inspect with a camera or only from the bottom. Confirm the arrival window and whether someone has to be home to let them in. Ask how they handle the hearth and whether they bring drop cloths or expect you to cover the floor.
Step three: clear the hearth the day before
Move the rug, the fire screen, the basket of kindling, and anything on the mantel that could get dusty or knocked over. Take the framed pictures down and put them in another room with the door shut. Cover the furniture nearest the fireplace with a clean sheet or drop cloth. If he has a favorite chair near the fire, let him pick a different one for the morning.
Step four: during the sweep
Open the damper and the clean-out door when they ask, and keep pets and small children out of the room. Ask the sweep to show you what they found before they pack up. If they point to a cracked liner, a damaged cap, or a bird's nest, ask them to write it on the paperwork, and ask what the next step would be and how soon it needs doing.
Step five: after the truck leaves
Vacuum the hearth with the right attachment, wipe the mantel, and put the pictures back up. Test that the damper closes all the way. Keep the inspection notes in the same folder as the house paperwork, so nobody has to call the company later to find out what they saw. If the house has a carbon monoxide alarm, check that it has a working battery while you are at it.