Correct Answer: Dev told his mother not to worry as they would soon find a way out of that crisis.

Solution : The second option is the correct choice.

The steps of conversion are as follows:

• The reporting verb "said" is changed to "told" in the indirect speech.
• The direct imperative "don’t worry" is transformed into "not to worry" in the indirect speech.
• The pronoun "we" is changed to "they" to reflect the shift from the first person to the third person.
• The conjunction "as" is added to connect the two clauses and convey the reason or manner in which they would find a way out of the crisis.

Therefore, the correct answer is: "Dev told his mother not to worry as they would soon find a way out of that crisis."