The correct answers are: The villain demanded to know where the secret vault was and ordered the agent not to tell anyone else. The villain inquired where the secret vault was and commanded the agent to tell no one else.

When reporting a wh- question, the word order changes from interrogative (verb-subject: "where is the vault") to declarative (subject-verb: "where the vault was"). Options with "where was the secret vault" are incorrect because they retain the inverted question word order.

When reporting a negative command, we use "not to + infinitive" (e.g., "ordered the agent not to tell"). Using "don't tell" in reported speech is grammatically incorrect.