The correct answer is option 2, which is the Prayaga Prashasti of Samudragupta.

Let`s dissect the other options to understand why they are not the correct answer.

Option 1 refers to the Nashik Inscription of Gautami Balashri. This inscription was actually composed by Gautami Balashri, who was the mother of Gautamiputra Satakarni. Therefore, it was not composed by Harishena.

Option 3 refers to the Deopara Prashasti of Vijayasena. This prashasti was composed by Vijayasena, who was a ruler of the Chaulukya dynasty. Again, it was not composed by Harishena.

Option 4 refers to the Hathigumpha Inscription of Kharavela. This inscription was composed by Kharavela, who was a ruler of the Mahameghavahana dynasty. It was not composed by Harishena.

Therefore, the correct answer is option 2, the Prayaga Prashasti of Samudragupta, which was indeed composed by Harishena.