Her tub caulk has pulled back from the wall, and from a phone photo it can look like nothing. Caulk is a small job, and it is easy to let it slide. The real question is whether you redo it on your next visit, send a handyman, or ask the local person who already works in her bathroom to take it on.
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.
Check the joint before you decide
Ask someone at the house, or ask her to take three photos: one straight on, one at the corner, one at the tile line. Note whether the old caulk peels off in a strip, crumbles, or stays put when pressed with a finger. Ask whether the rim of the tub feels solid or whether the floor gives when someone stands beside it. A gap is a caulk job. A soft or spongy spot means water has reached something structural, and that belongs to a pro who can look behind the wall.
Do it yourself when
The old caulk comes out in one piece or with a plastic scraper and a little softener. The tile and grout are sound. The tub can sit unused for the time the label asks. Someone at the house can follow the product label for surface prep and curing time. You will need a caulk gun, a sealant labeled for tub and tile (these are usually silicone), painter's tape, a scraper, and rubbing alcohol. Keep the bathroom door closed while you work, and ventilate the room.
Hand it to a pro when
Tile is cracked or loose, grout is crumbling in large sections, the floor flexes, or the wall behind the tub shows staining that comes back after cleaning. Also hand it off if nobody local can be there for the work and the drying time. At that point the job is less about the tube of sealant and more about who can open the wall if something is wrong behind it.
Questions to ask before the work starts
Ask whether they remove all of the old sealant or lay new caulk over it. Ask what they do if the wall behind the tub is soft. Ask how long the tub must stay unused and who tells her when it is ready. Ask whether the work is guaranteed in writing and for how long. Ask for a one-page estimate that lists removal, new sealant, and any repair they find, so you are not surprised by a second line on the final bill.
Tonight
Ask her for three photos and one question: does the tub edge feel solid when she stands next to it? Write down what she says. If the answer worries you, keep the tub off the list until someone has looked at it. Then set the next step: a visit with a caulk gun, or a call to a local handyman with the photos and the questions above. If you need a name near her house, the St. Louis help page is a good place to start: Local Help for a St. Louis Parent.