@ Poornima For which I am charged interest of 1 day @ 1.5% per month in justification report, it's written by Maya in question. @ 1.5% per month (for 2 months, might be possible she forgot to mention :P ) .
But whatever the case may be, as per fact given in question, if we assume tds was deducted in 30th of the month i.e. last day of month but deposited at 1 day delay, so in that case section 201(1A) clearly mention that interest shall be charged @ 1.5% for late deposit from the date of deduction.
Here we can conclude the first day after deduction would be next day of deduction i.e. 1st day of next month i.e. deposit wala month. So in this case it's right, interest is correctly charged @ 1.5% for 1 month only.
On the other hand, if deduction had been made any day except last day of month, then surely interst would have been charged for 2 months.
So your answer is correct but you didn't consider the date of deduction. Co-incidently deduction date was last day, therefore answer is correct :)