Whether i can file IT for AY 16-17 , 17- 18 now?

Dear Friends,

I want to file my IT for the AY 16-17 & 17-18 now. Shall I file my return under after due date sec 134 (4)

Because I was search regards this. I found 2 answers. please tell me which one is correct.

1) after due date for AY 1617 is 31st March 18
2) 2 year time limit after last date AY 1617 so 31st March 19.

which date is correct???

Regards ,

Bala