A loose porch rail looks like a weekend job, and sometimes it is. But a rail is there to hold a person's weight, so the choice between doing it yourself and hiring it out turns on what the rail is attached to, not how hard the fix looks. Dad may say the rail has held for years. Test that with your hands before anyone picks up a drill.
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.
Test the rail before you touch it
Push the rail at the top and at each post, first gently and then firmly. Note whether the rail moves, the post moves, or both move. Check every connection: where the rail meets the post, the base of the post where it sits on the deck or step, and the framing it bolts into. Tap the wood for softness, and look for dark rot, split or cracked boards, rusted fasteners, and gaps that open when you push. Photograph each connection before you change anything.
Do it yourself when the problem is small
A DIY repair fits when the post and framing are solid, the only failure is fasteners or a loose bracket, you can reach every anchor point from a stable position, you can replace the parts in the same size and spacing you found, and a second adult can hold the rail while it is secured. If all five are true, you are making a repair, not a rebuild.
Hire it out when the structure is in question
Hire the job when the post base is soft or rotted, when the rail is fixed only to the face of a step or deck board, when the stair or landing moves underfoot, when the rail is the only support he uses to get in and out of the house, or when the fix means cutting into framing. Ask any contractor who pulls a permit if one applies in your town, and who inspects the finished work. Ask the question rather than assuming the answer.
What to ask each bidder
Compare written scopes, not totals. Ask each company whether it will replace the rail or only tighten it, what material and fasteners it will use, what it will do if it finds rotted framing under the post, whether the post base is in the price, whether the work is inspected and by whom, how long the workmanship warranty runs, and who clears the debris. Flag any line that says the work will be done as needed, because that is where the extra charge tends to hide.
The next move tonight
Tonight, take a flashlight and a screwdriver outside, push the rail at the top and at each post, and photograph every connection. Send the photos to two companies and ask each for a written scope in the same format. For a starting list of local help in St. Louis, see Local Help in St. Louis.