Identify B formed in the reaction.

$\mathrm{Cl}-{\left({\mathrm{CH}}_2\right)}_4-\mathrm{Cl}\stackrel{\mathrm{excess} {\mathrm{NH}}_3}{\to }\mathrm{A}\stackrel{\mathrm{NaOH}}{\to }\mathrm{B}+{\mathrm{H}}_2\mathrm{O}+\mathrm{NaCl}$

Substituted ammonium salt is formed when chloroalkane reacted with excess of ${\mathrm{NH}}_3$, which on reaction with $\mathrm{NaOH}$ gives $1,4-\mathrm{diaminobutane}$.

The carbon - halogen bond in alkyl halides can be easily cleaved by a nucleophile. Hence, an alkyl halide on reaction with an ethanolic solution of ammonia undergoes a nucleophilic substitution reaction in which the halogen atom is replaced by an amino group. This process of cleavage of the $\mathrm{C}–\mathrm{X}$ bond by ammonia molecule is known as ammonolysis.  Substituted ammonium salt on reaction with sodium hydroxide gives 1,4-diaminobutane as shown below,

Hence, the answer is option B.