They made a lot of money by cheating and ill-treating ir labourers who worked in ir fields.

Clearly, option A is right answer.

... A year went by, and because of Manikya’s hard work, Amrutananda had an excellent harvest. He and his wife Mandakini, decided to have a big feast to celebrate. ...

It's clear from first few sentences of 3rd paragraph of passage that Amrutananda and his wife wanted to celebrate because y had an excellent harvest.

Option C hence is correct answer.

As per passage Amrutananda’s wife was not bitten by a cobra snake. It was a lie which was intentionally told to Amrutananda by Manikya. 

Option A hence is correct answer.

... “Remember my condition, that I would lie only once in a year? Well, I choose today. You see what lies can do? They nearly destroyed your life. Now think about what happens to people you lie to everyday. Saying this he walked out ...

Out of given choices most appropriate title of story would be "Manikya- wise labourer".

Option B hence is correct answer.

... “Remember my condition, that I would lie only once in a year? Well, I choose today. You see what lies can do? They nearly destroyed your life. Now think about what happens to people you lie to everyday. Saying this he walked out ...

Out of given choices, moral of story would be "Lying destroys lives".

... “Remember my condition, that I would lie only once in a year? Well, I choose today. You see what lies can do? They nearly destroyed your life. Now think about what happens to people you lie to everyday. Saying this he walked out ...

From last paragraph of passage it's evident that Manikya wanted to teach Amrutananda a lesson.

Option D hence is correct answer.