She claims to want only something light-hearted, fun, and empowering. She's a "butt kicker" to use the old appeal term. That seems difficult to do in the OSR.
I don't think it's impossible, though. One of my players in my three year campaign, who played the main fighter, is rather like this (though he gets into some intensive RP as well). He definitely got a bit frustrated and complained at times in particularly difficult encounters and/or when the dice gave them an uphill climb.
But he rolled a character with a reasonably high Str and Con (and therefore HP, plus he made one character advancement decision which gave him some bonus HP), and he kicked a lot of ass. The flip side to character fragility in OSR games is that the monsters are also more fragile. They have lower HP, do less damage than in modern editions, and often die to a single spell (sometimes with no save, as with Sleep, or with a roll to cast game like 5TD or SD). And if you actually use Morale rules they even run away sometimes.
I remember you talking in another thread about your wife enjoying big damage numbers. One thing OSR games usually do is reduce the numbers overall, but when the average Orc has 5 HP, a d8+2 damage Fighter (normal sword and 16 Str in B/X, or 13 Str with a +1 sword) is getting one-shot kills on 75% of their hits. The Fighter needs to roll an 11 or better to hit, so one shot kills against them are only 37.5% of his attacks, but compare to a 5E 1st level Fighter and Orc- most likely d8+5 (assuming 16 Str and dueling style) vs 15 HP (only ever one-shot killing on a particularly good critical). The 5E Fighter has a better attack bonus (+5 vs AC 13) so only needs to roll an 8 or better to hit, but you can see how the B/X Fighter at the baseline is more deadly.
I like to give my B/X Fighters the "sweep" rule to multi-attack low HD foes too. Other folks like the Cleave house rule (extra attack whenever you drop an enemy). Either one can turn an OSR Fighter into a cuisinart against low level baddies.
I feel like DCC is also intended to support butt-kickers, with all the sweet stuff Warriors can do with Mighty Deeds, and the nutty critical hit charts. But the player does have to be able to roll with the punches of random fumbles, too.