A good PvM bowazon is one of the most difficult builds after the 1.10 patch. From my personal experience with strictly PvM bowazons, the first thing you must ask yourself is the purpose of this zon: is she going for leveling, is she going for the ubers or is she going just for fun?
Meanwhile, take note of the following:
*In order to stay alive in Hell, a bowazon must be able to kill her enemies before they touch her. Besides maxing resistances (especially lightning) there are only two ways to do this. Freeze them with Freezing Arrow or zap them with Multishot and high speed. Magic Arrow is a good choice for the Physical and cold immunes. Lowering enemie's cold resistances and immunities (with items) is also extremely useful, especially against Bosses.
*Maxing Valkyrie is not necessary. She will stay alive more than your high lvl merc even with only 10 points.
*Holy Freeze and Concentration auras can increase your zon's total damage. So far I havent seen a bowazon able to deal more than 10k total dmg. And this doesnt help at all against Baal or - even worse - against the Ubers. If they can tank and deal massive physical damage at insane speed and their team is strong (smiters are neccessary) they might stay alive at Uber Tristram