The correct option is A Sid told you that he would help you in your project.
When a sentence is changed from direct to indirect speech, the subject
pronoun, verbs and tense forms also change. (This is because the speech is reported by someone else, and the tense
of the direct speech goes one tense back as it's spoken at a later time
now.) The meaning of the sentence
should not differ.
Option B: This sentence is the correct narration
of the direct speech, as 'I will' is changed to 'he would'. 'Would' is the past tense form of 'will' in indirect speech. Also, 'you' remains the same as the listener (object of the reporting verb 'said') remains the same (Sid told you). Hence A is correct.
Option A is incorrect because the second person 'you' in the indirect speech does not change to 'him'. As mentioned outside the direct speech, the speaker Sid delivered the speech to the listener 'you'.
Similarly, option C is incorrect because 'you' does not change to 'me'.
Option D is incorrect because the speech in A is incorrect.
'Said' and 'told' don't mean the same thing, but 'said to' means the same as 'told'.