Ionic hydrides are, usually :

Ionic hydrides are usually good reducing agents.

The active metals, such as sodium, magnesium, aluminum, and zinc, which have relatively low electronegativities and fewer ionization energies, are good reducing agents. Metal hydrides that technically include the H^- ion, such as $\mathrm{NaH},{\mathrm{CaH}}_2$, and LiAlH₄, are likewise effective reducing agents.

Hence, the correct option is C.