Step 1: Understanding the reaction.
This reaction involves the use of sodium amide (NaNH$_2$) and ammonia (NH$_3$) in the presence of a chlorinated compound. Sodium amide is a strong nucleophile and will replace the chlorine atom in the chlorinated compound, leading to the formation of an amine. The reaction leads to the formation of a hydrazine (H$_2$N-NH$_2$) derivative.
Step 2: Conclusion.
The correct product formed is hydrazine, corresponding to option (B).