Malah is a Diablo II NPC, and is a merchant and a healer found in Act Five. Kindly, elderly, but still hale, Malah dispenses wisdom, quests, and rewards, but without showing weakness or sorrow over the plight of her defeated people. As a merchant Malah specializes in magical weapons, including staves, wands, and scepters. She also sells healing and mana potions, keys, and books/scrolls, along with throwing weapons and a few types of armor.
Malah's location right beside the town portal appearance area is quite convenient for quick trips to and from town, so long as repairs are not needed. Most players don't bother running down to Deckard Cain while in Act Five since it's quicker to identify items right at Malah, especially since she sells ID scrolls.
Since we don't know for sure what happened to the people of Harrogath, her fate is uncertain. She could have survived, but the massive explosion of the Worldstone could also have been fatal...