You could totally go with it, and have the attacker(s) be complete scum-bags, with the character's vendetta actually resulting in the rescue of their latest victim(s). They might even have a personal dungeon beneath the mages shop / manor / quarters, holding people they've captured and are selling into slavery on the underground market. Killing them ends up being a heroic deed, a public service and morally as uncomplicated as can be.
You could turn it into a plot-advancer, and have the attacker(s) be connected to some darker group that the player(s) will be dealing with anyway. Perhaps the assault was part of the NPCs initiation rites into a cult of murder or brutality, in the service to a god of evil, or even a demon lord's cult, and in taking them down, the PC finds brands hidden beneath their clothing or secret cult talismans on their person or other damning occult parephenalia in their quarters, linking them to this secret society.
You could play against it, and have the attacker(s) have been under some sort of mental possession from bodiless entities from beyond, who 'joyride' in people's bodies and make them do all sorts of extreme things (particularly those that result in extremes of sensation, which is something the bodiless possessors don't get to experience otherwise). The possessors could still be in those bodies, and the players actions could end up revealing them, inadvertantly 'saving' her attackers in the process of killing them, and discovering that these creatures exist, and, much later, discovering that there are *more of them,* as people begin to move against her, as the possessing-entities have seeded themselves into various strata of society and don't want their true natures discovered. (They might not be bodiless either, they could just be dopplegangers or something, and, unaware that they were going to spend some serious infiltration time in these bodies they'd taken, they victimized the character in a manner which they would normally only do in a 'disposable' form.)
You could *totally* play against it and have one of the attackers be dead (worse yet, being remembered as a hero to the villagers he died saving from a hobgoblin seige! Statue to his honor and everything, all Jaynestown style.), and the other having shaved his head, renounced his titles and joined the clergy of a god of peace and justice, spending his life in what he believes to be a futile attempt at redemption for his reckless youth. He'd be really hard to track down, having abandoned his family name, but, when confronted, tell the character that if his life can in anyway help her heal from what has happened, she is welcome to take it. If any comment about redemption is made, about escaping his misdeeds, he'll stress that there is no such thing as redemption in this life, and that he'll only find it in death, whether that be immediately, or after another fifty years of dedicating his life to good works.
If the player has real-life issues with this sort of situation, it might be best to deal with it very, very quickly. "You find them. They are scum-bags. You kill them. The villagers they've been oppressing cheer and have a big party for you."
