Explanation:

Correct Answer is (c).The sentence is not grammatically correct since it is about the event that many of the friends of the person came to see him in order to give him congratulations on his success. The given phrasal verb called to does not imply this as it implies shouting to somebody to draw the attention.
Among the given options, called off implies cancelled whereas called on refers to paying a visit to somebody. Other options are out of context and that is why they cannot be considered for this.
The correct sentence would be: After my success in the competitive examination, many of my friends called on me to congratulate and also to give best wishes for future.This makes option C the correct choice among the given options.