What to do tonight
Take the box or boxes out of the closet and count them. Do not open the envelopes yet. Write down roughly how many there are, what kinds of pictures are in them (prints, slides, negatives, or loose snapshots), and which ones would hurt most to lose. Keep that list on the kitchen table. It becomes the first question you ask every service.
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.
Ask every service the same questions
Before you compare any two services, send each one the same list of questions and ask for the answers in writing. Ask where the scanning happens and who handles the originals from the moment they leave your hands to the moment they come back. Ask whether slides and negatives are included or billed separately, and whether they will scan a small test batch before you commit to the whole collection. Ask what file format and resolution you receive, and whether you get a full set of files or a compressed set. Ask how the scans are delivered: a download link, a drive, or a disc. Ask whether they add names or dates to the files, or whether that is your job.
Read the terms about the originals
Read what the terms say about lost, damaged, or misplaced photos before you agree to anything. Look for the value they state for an item, and whether the language promises a replacement, a refund, or only a limited refund. Check whether originals come back in the same box or in a separate package, and how long the company keeps them before shipping them back. Find the cancellation clause too, and whether cancelling after the first batch still lets you keep the scans you already have. If a service will not put any of this on paper, treat that as the answer.
Put the box back together
When you pack the box to ship it, take a photo of the contents and the packing with your phone, and write the shipping date on a card inside the lid. Keep the tracking number in the same place. These small steps are the difference between an easy question later and a long argument about what was sent and what came back.
When to stop and ask Dad
Some of these photos belong to him as much as to you, and he may not want some of them sent out at all. Before anything ships, sit with him, show him the list of what is going, and ask whether there is any picture he wants to keep in the house or see first. He may say no, and that is worth knowing before the box leaves. If you are in St. Louis, the local help page for a widowed father is a place to start asking around for options near you, and it is worth comparing whatever you find with the list above.