I believe the book being referred to is Sitara Khan, A glimpse through Purdah: Asian women -- the myth and the reality (Stoke on Trent, Staffordshire: Trentham Books, 1999). I obtained this book from the librarian, and found the following quotation:
Muslim women who had had the right to inherit property and wealth in
their own right and keep their earned income were particularly
affected. Their rights were brought into line with those of Hindu
women, who could only 'safe-keep' the land for their minor sons, and
whose only 'inheritance' came in the form of dowry upon her marriage
-- and which was handed to her husband's family. (pp.14-15)
There is no citation for this, nothing that looks like a citation anywhere near it, and no date for the supposed removal of rights, and I find the entire content of this book quite dubious.
Apparently more information about this can be found in Shahida Lateef's Muslim women in India: political & private realities, 1890s-1980s (1990). Lateef is quoted in another book as saying that "the difference was a matter of region, class and caste, more than religion."
Lateef's book is at a library I can access, but I think this is probably enough information to put considerable doubt on the claim.