Hydro and Pyro are valid options for the reasons you provided.
Alternatively, as the Ranger is Dex based you also could add one or two Scoundrel levels. There are many Novice Scoundrel skills a Ranger can profit from, e.g. Fast Track to haste her without Wildfire's heat effect, Winged Feet for positioning over/on harmful surfaces, Hide in Shadows for protection from advancing enemies, to name a few.