The question at hand is about identifying the composer of the 'Prayaga Prashasti', also known widely as the Allahabad Pillar Inscription.

Let's break down the options:

1. Kalidasa in Sanskrit: Kalidasa was a renowned classical Sanskrit author, widely regarded for his plays and poetry. However, there is no historical evidence linking him to the creation of the Prayaga Prashasti.
2. Banabhatta in Sanskrit: Banabhatta was a 7th-century Sanskrit scholar and poet. He was a court poet of King Harshavardhana and is known for works like 'Harshacharita', but he is not associated with the Prayaga Prashasti.
3. Harishena in Sanskrit: Harishena was the court poet and minister in the court of Samudragupta, a ruler of the Gupta Empire. Harishena is credited with composing the Allahabad Pillar Inscription, which is a eulogy of Samudragupta’s conquests and his political and cultural accomplishments.
4. Ravikriti in Sanskrit: Ravikriti was a poet in the court of King Harsa of the Chalukya dynasty, but he was not related to the creation of the Prayaga Prashasti.

In conclusion, the correct answer is:

The Prayaga Prashasti (Allahabad Pillar Inscription) was composed by Harishena in Sanskrit. This inscription serves as a significant historical text, providing insights into the political, cultural, and military prowess of Samudragupta.