The correct option is B has gone
The first sentence "Tom is away on holiday" implies the tense of the second sentence. The former states that 'Tom' is already on holiday.
Option C: 'Has gone' is in the present perfect tense. It indicates an action that happened sometime in the past, but has an effect on the present. In other words, 'Tom went to Srinagar (an action that happened in the past), and he is on holiday (the state in the present).'
Hence, option C is correct.
Option A: 'Will go' states the future, an action that is yet to happen. But the action has already happened, as 'Tom' is already on holiday. Hence option A is incorrect.
Option B: 'Is going' is in the present continuous tense. It states an action that is happening now. But the action 'to go to Srinagar' is in the past. Hence B is incorrect.
Option D: 'Has went' is grammatically incorrect. 'Has' forms a present perfect tense, using the past participle form of a verb ('gone') and 'went' is the simple past tense verb, which does not use an auxiliary 'has'. Hence, D is incorrect.