Thank you, again, for encouragement. I would say that the most American tools would be a 50bmg or a 30bmg or a (real) BAR or a 1911 or a Hi-Power or an Auto 5 or anything else (even a Baby .25) by the John "me, genius?" Browning.
However, my parents not being into complex guns, I can see arguments for something simpler. They have, for example, a distinct preference for a Glock over a Makarov, because the Glock has simpler manual of arms.
I think a 77/22 would be a possibility, along with a 2x36 or so scope (does ANYONE still make rifle or shotgun scopes that are fixed low magnification, say 1x or 2x with decent light gathering?)
However, my father is not into rifles, so a Ruger Mk2 stainless with a scope might be the ticket. Too bad single-action revolvers are out, too complex to operate. A S&W 617 might work, too.
Neither of them likes noise or recoil, so .22 might be a good choice. OTOH, I can see an argument for a 4" S&W66, so they can get used to having a defensive gun that is their own, rather than a loaner.