Clubbing of trading Income tax

Since it is revocable transfer therefore clubbing provisions will get attracted.

Since the income is being clubbed in your income therefore it will not be taxed in the hands of your relative.

So we should not file the return for my relative even though income is above 5 lacs ? or do we need to file and there is any option to indicate that the income is already clubbed with son-in-law account ?

No your father is not required to file ITR for this income unless he has his other income exceeding minimum exemption limit.

But the income is exceeding the minimum exemption limit, so how do i file the return for her and indicate that the tax is already clubbed through my hands ?

File the return for other income, check  whether there is any provision in the ITR to show for income already clubbed.

As per my opinion, there is no such provision in the ITR.

While filing your return show the said income under clubbing head/subhead.