Question

we had only reached Pune and still had____ to arrive at my grandfather's village​

Answer 1

We had only reached Pune and still had been trying to arrive at my grandfather's village.

Explanation:

Incomplete sentence:

we had only reached Pune and still had____ to arrive at my grandfather's village

Complete sentence:

We had only reached Pune and still had been trying to arrive at my grandfather's village.

As the first clause is in past perfect the second clause will be in past perfect continuous tense.