Statutory maternity benefit to a woman (employee) is in the form of authorised absence with salary/wages calculated on average basis of her earnings during the immediately preceding 3 months for a period of 26 weeks. The only condition for the grant of this benefit is her completion of 80 days of service in the establishment during the 12 months immediately preceding her expected date of delivery as certified by a registered medical practitioner. No other conditions can be added by the employer according to his choice.
Resignation is the unilateral termination of the contract of employment by the employee at will and is simply governed by the conditions of notice only. Therefore, grant of maternity benefit by the employer or its enjoyment by the employee can not be a condition for acceptance of resignation.
From the particulars given in the post her maternity leave continues till some time in April,2019. As such she can avail the entire leave and then resign but has chosen to resign in the middle. It implies that she has got her own compelling reasons to do so.
Therefore, you can adjust the notice period in the leave and accept her resignation.
21st January 2019 From India, Salem