Diborane undergoes cleavage and gives adduct with
(i) CO
(ii) $H_{2}O$
(iii) $NM{e}_3$
(iv) $N{H}_3$

The correct option is B i, iii
(i) and (iii): Diborane undergoes cleavage reactions with Lewis bases (L) to give borane adducts, $B{H}_3.L$
$B_2{H}_6+2NM{e}_3\to 2B{H}_3\cdot NM{e}_3$
$B_2{H}_6+2CO\to 2B{H}_3\cdot CO$
(ii) diborane gets hydrolysed readily to give boric acid.
$\underset{\text{Borane}}{B_2{H}_6}+6H_{2}O\to \underset{\text{Orthoboric acid}}{2H_{3}B{O}_3}+\underset{\text{Dihydrogen}}{6H_2\uparrow }$
(iv) Diammoniate salt complex is formed
$B_2{H}_6+N{H}_3\left(\text{excess}\right)\stackrel{\text{low temperature}}{\to }{B}_2{H}_6.2N{H}_{3}or\left[H_{2}B\right(N{H}_3{)}_2{]}^{+}[B{H}_4{]}^{-}$
Hence correct option is b.