Maternity Benefit and Notice Period
Hope she has received Maternity Benefit from the employer. If this assumption is correct, then the employer is also justified.
If the terms of employment state that you need to serve a three-month notice to the company, you are required to adhere to it. Alternatively, if you want to be relieved earlier, there is NOTHING WRONG in adjusting the amount payable for the balance notice period against the dues payable to you.
How can you expect the employer not to deduct the notice period pay? I am asking a question. If the same employer communicates with you (or your wife, for that matter) that you are no longer required in their services (or from a particular date) when you come to the office for signing the muster, how would you react? Would you not expect some notice period to apply for new jobs, collect your offer/appointment letter, so that the exit process would be smoother?
If you agree with this point, then the employer also has the right to expect you to serve the notice period for him to locate a potential candidate to be put on the job, train him, and take over the charge from the outgoing candidate.
The Rubber Ball Analogy
I always believe that when you do good things (irrespective of others doing good to you or not), you will receive good deeds. It is like a "rubber ball" thrown on a wall. (You play this and see for yourself). When you throw a rubber ball on the wall, the speed or pressure with which you throw, with the same speed, it comes back to you. (I have played myself and learned a message from this).
It is up to you to decide to adhere to the company's rules or kick the employer and vanish without any information.
Regards,
Balaji