I think you are working in an organization in the area of Maharashtra. If so, the rules as framed by the State Government under the Act will also be applicable for compliance, as mentioned earlier.
In my opinion, there is no utility in reading old and lengthy books on the subject because there are often amendments in labor laws that are not reflected in older books. I suggest that you purchase an updated Bare Act of the Maternity Benefit Act, 1961, along with the Rules framed by the Maharashtra Government (if applicable) and decide the issue accordingly.
As I understand, for entitlement, it is mentioned in the Act that "no woman shall be entitled to maternity benefit unless she has actually worked in an establishment of the employer from whom she claims maternity benefit, for a period of not less than eighty days in the twelve months immediately preceding the date of her expected delivery (Section 5(2))." There are exceptions and explanations in this section that you should review before making a decision. The eligibility conditions were previously "one hundred and sixty days," which were amended in 1989.
The provision of medical allowance is mentioned in Section 8 of the Act. As per my information, it is presently Rs. 3500/- to be paid under certain conditions specified in the Act. I hope you will take action in accordance with the provisions of the Act and the rules applicable in your case.
Regards