"have narrowed my choice down to these"
I won't 2nd guess you.
I would go with either of your top two, call it a toss up, flip a coin
S&W 642 or Taurus Model 85
but I would not recommend the others to close family
"wondering if the other guns are reliable, especially the Taurus"
Taurus gets a lot of very legit criticism, because they earn a lot of criticism, but not all their handguns are created equal. The series 85 earns good marks on every forum I have seen, and I have shot a couple myself (though I don't own one). I like 'em, they compare just fine with my S&W old model 60 snubbie.
So, I would have a tough time calling that coin flip, but for me, I would go DA/SA anyway, not DAO. Don't know your mom's preference on that, maybe she has such a preference, maybe she doesn't. Most do prefer hammerless DAO for "carry".
as for the S&W ILS thing, I could care less
Matters not to me unless talking 357 mag or heftier loads in airweights, which I do not recommend with or without ILS, anyway. Be "Mom friendly", stick with all-steel weight for 38+P stuff. 38+P is stout enough for any 2" snubbie, 357 is more flash-n-boom, but extreme little ballistic gain, and a handicap to shooter followup. Me, I don't even bother with using 38+P in less than 3 inch barrels, but lots of folks do.
good luck
Mom will smile, whatever you pick, mom's are like that, they are