To solve this question, the user needs to know about the Allahabad Pillar Inscription and its association with a particular ruler.

The Allahabad Pillar inscription is associated with Samudragupta, who was a ruler of the Gupta Empire. The inscription, which is written in Sanskrit, contains information about Samudragupta's military campaigns and achievements. It is considered to be one of the most important historical records of the Gupta period.

Now, let's go through each option and explain why it is right or wrong:

A. Ashoka: This option is incorrect because the Allahabad Pillar Inscription is not associated with Ashoka. Ashoka was a ruler of the Maurya Empire, which predates the Gupta Empire by several centuries.

B. Mahapadma Nanda: This option is incorrect because the Allahabad Pillar Inscription is not associated with Mahapadma Nanda. Mahapadma Nanda was a ruler of the Nanda Empire, which also predates the Gupta Empire.

C. Samudragupta: This option is correct. The Allahabad Pillar Inscription is associated with Samudragupta, who was a ruler of the Gupta Empire.

D. Chandragupta Maurya: This option is incorrect because the Allahabad Pillar Inscription is not associated with Chandragupta Maurya. Chandragupta Maurya was also a ruler of the Maurya Empire, and his reign predates the Gupta Empire by several centuries.

Therefore, the answer is: C. Samudragupta.