1) Agree entirely with the premise that you can answer "none, but..." to any query. If you are the expert, relatively, that's your expertise. 90% of my day job is saying (usually more nicely: that's a stupid request, let's dig into WHY you want that and come up with a solution).
2) I keep seeing people say a revolver is simpler to operate. Prove it. I have tried. Give 10 minutes of instruction in the basic operating principles and manual of arms of a semi-automatic handgun: give people the gun. They will use it, with adequate proficiency. Most everything is pretty obvious and easy to use in modern day firearms. Now, give the same person 10 more minutes on the revolver and let them have a go: they will struggle to shoot or operate it well. Just reloading is stupendously un-obvious, so you can show them the ejector rod, have them try it, then see them either vaguely gazing at the gun in wonder or trying to pick the shells out with their fingernails a few minutes later when they have shot it dry. If they can get the cylinder open.
3) If they think a firearm is all that will help: a simple 9mm handgun with as much capacity as you can get. Whatever is reasonably trustworthy (glock, M&P, whatever is available at the LGS), with NO controls but trigger and magazine release. No fussing with hammers, decockers, safeties. Max capacity as they will fail to even THINK about reloading if a situation arises when they need it, and they are not gonna train.
3a) Try to get them to pony up a few bucks for a laser/light combo, ideally set up to come on automatically (e.g. when pulled out of a holster). Avoids accidents (they can see that it's their daughter sneaking home) and improves hit percentages a lot. Stuff I wouldn't necessarily trust the way I use my guns, like Viridian, have inexpensive ones that do this, will work just fine for a "nightstand" gun.
4b) YES 1000% to making them buy a lock bock or reliable other lock for the trigger or something. Make them use it. Tell jokes about how kids are the only ones to open kid safe caps to drive it home. Remind them thieves look for hiding spots For A Living. Lock, do not hide or hope.