Explanation:

Let's break down the sentence to identify any grammatical errors:

- (A) Mahendra Singh Dhoni, over the next decade,

- This part is grammatically correct. It sets the timeline for the events discussed.

- (B) herald a new era for Indian cricket,

- There is a grammatical error here. The correct form should be "heralded" to match the past narrative tense set by the rest of the sentence.

- (C) even as the World Cup firmly established the newest version of the game,

- This part is grammatically correct and aligns with the past tense narrative.

- (D) which had till then stumbled along with a whiff of irrelevance.

- This part is correct and appropriately uses the past perfect tense.

- (E) No error

- Since we found an error, this option is not the correct choice.

The highlighted option should be Option: 2, B because it contains the grammatical error.

Thus, the correct answer is:

Option: 2, B