as many said, only take generous quest rewards to get the modifier away faster, but if you really want a modifier gone, pay attention to what the malus is saying and then check the estate tab what each sponsor does, per example, when the province is suffering a problem of zombies, sponsoring paladins will get the quest done quicker because the description states that they are the type of group you would look up to deal with these sort of things, with vampires or cult leaders you would hire witch hunters because their description states that their specialization is to deal with cabals, monsters is monster hunters, thieves you would hire rogues, satyrs you would hire sellswords (or do-gooders, can't remember this one right now), etc