I would LIVE for an Avernus location and getting to play through a proper quest for her. I would also love to save her without having to put her though Avernus at all.

However, now that the option has been brought up, I think I personally would be content with an epilogue where Karlach and whoever went with her come back to meet with their friends again - provided that they come back victorious with her healed. Let her kick the door down like SUP GUYS GUESS WHO'S RUSTY OLD HEART GOT A MAKEOVER and hug every party member or all of them at once.

I'm sure having her come back only to later return to the Hells AGAIN wouldn't make anybody happy though.

[Linked Image from tarraxahum.neocities.org]