Solution
Option 1 -> This idiom suggests being satisfied with what you have rather than risking it for something uncertain, which doesn't match the postmaster's longing for the city.
Option 2 -> This idiom means being separated from something makes you appreciate it more, which perfectly describes how the postmaster increasingly yearns for Calcutta while stationed away from it.
Option 3 -> This idiom means don't be critical of something given freely, which is irrelevant to the postmaster's situation and feelings about city life.
Option 4 -> This idiom suggests perceiving other situations as better than your current one, which fits the postmaster viewing the city as superior while stuck in the village he considers uncivilized.
Hence, Options 2 and 4 -> The postmaster's exile in Ulapur intensifies his longing for Calcutta ("distance makes the heart grow fonder"), and he romanticizes city life with its "metal roads" and "tall houses" while feeling miserable in the village ("the grass is always greener on the other side"). His yearning is captured in the line "The city was spreading its tentacles, calling him back" -> correct