Dear Antony Edgar,
End of relevant assessment year in this case is 31.03.2014 and not 31.03.2015.
As per Section 271F
"If person who is required to furnish a return of his income, as required under subsection (1) of section 139 or by the provisos to that sub section, fails to furnish such return before the end of the relevant assessment year (Which in this case is 31.03.2014), the Assessing Officer may direct that such person shall pay, by way of penalty, a sum of five thousand rupees.
So by reviewing this section carefully, your answer will be as follows.
1) Since your total income does not exceed basic exemption limit, hence you are not required to file return, but still even if you want to file, then penalty u/s 271F cannot be imposable as you are not required to file return.
2) Even if you’re total income exceed basic exemption limit, still whether to charge penalty or not is upon AO. It is his discretionary power as word "may" is used in section. So even if he charged penalty (in case total income exceed basic limit) still you can make penalty waiver application if you have reasonable cause for delay.