The correct option is
A (a)
In English, usually, the verb follows the subject. For example; "He realised"/ "He did not realise'. Inversions are mainly used when the sentence begins with a negative word. When a sentence starts with the word, "little', it is used in a negative sense. Hence, in such a sentence, the subject and verb are inverted, along with the use of an auxiliary.
The phrase, 'Little he realised' in the beginning of the sentence is grammatically incorrect. The subject is 'he'. The verb is 'realised'. The auxiliary to be used is 'did'. The correct inverted phrase is: 'Little did he realise'. It means the same as 'He did not realise'. As part (a) has to be modified, option A is the correct answer.
The modified, correct sentence is: '(a) Little did he realise (b) that he wouldn't live (c) to see his grandson married'.
As parts (b) and (c) do not need to be modified, options B and C are not the answers. Option D is not the answer as part (a) is erroneous and has to be modified.