The Hydride that is electron deficient is ___?

The Hydride which have less than a octet per central atom or scarcity of electrons to form chemical covalent bonds is called electron deficient Hydride

${\mathrm{B}}_2{\mathrm{H}}_6:$electron deficient , ${\mathrm{NH}}_3\text{ and }{\mathrm{H}}_2\mathrm{O}$: electron rich 

${\mathrm{CH}}_4$ : electron precise