(N/A) Saline hydrides (e.g.,$NaH, LiH$) react with water to form a base and hydrogen gas.
The chemical equation for the reaction is:
$MH_{(s)} + H_2O_{(l)} \to MOH_{(aq)} + H_{2(g)}$
This reaction is violent and produces fire.
$CO_2$ is a well-known fire extinguisher because it is denser than air and acts as a blanket,cutting off the supply of dioxygen $(O_2)$ to the fire.
However,$CO_2$ cannot be used to extinguish fires caused by saline hydrides. This is because saline hydrides are strong reducing agents and can reduce $CO_2$ to carbon (soot) and metal carbonates/oxides,which can further fuel the reaction or cause an explosion.
$2MH + CO_2 \to M_2CO_3 + H_2$ (or similar reduction products).
Therefore,$CO_2$ should not be used.