Hello Sir, Basic exemption limit for an individual is Rs. 250000/-. In case of senior citizen I.e age above 60 years it is Rs. 300000/-.
If she is a salaried employee then you should show her salary income and rent income with interest Income, if any. You should apply for pan card first online and start filing the returns.
As you are paying rent to your parents showing it in their return is necessary and should keep document executed between both of you duly signed on revenue stamp and payments through bank account.
Please let me know if any further query. Thanks