Nri receiving rent in mothers account

Hi,

I am a NRI having 1 flat in india. The rent is received by my mother in her SB a/c. Now , how to file income tax?

1) Show it as rent received in my mother's IT returns?

OR

2) show as gift from daughter in my mother's IT returns as she does not own the Flat , still receiving rent every month?

OR

3) should I file IT returns in India? I have PAN, but no other income in india..and this rent is Rs.15000 per month.

Please tell me the correct legal way of doing this.

Thanks.