Dear Shruti,
Thank you for your query! I am Aadil and I will try to answer your question.
The short answer to your question is NO. Such a will cannot be challenged.
Ancestral property laws in India are governed by the Hindu Succession Act, 1956. The definition of an ancestral property as per the same is as follows; any property that has been passed on for four generations by male ancestors, which, during this time, was not divided, partitioned, or sold in any way. If the property is partitioned, sold, or divided during this time, it loses its status as an ancestral property.
The key point to be noted here is that the property must be passed on by male ancestors. This means that ancestral property can exist only from the side of the father, and not from the maternal side.
Another fact that must be noted here, is that your mother inherited this property from her father who died intestate. She did not succeed him, meaning that this property is most probably self acquired and cannot be treated as ancestral. If the property is self acquired, she will have complete ownership over the same and may choose to sell it to whoever she prefers. Her legal heirs cannot raise any objection over this.
Your mother’s argument is also right that it has been mentioned in the Hindu Succession Act, 1956, that any property received by any female, either through inheritance, succession, gift, or any other mode of transaction, shall be treated as absolutely her own property.
Therefore, the property in question is her self acquired property and no objection can be raised if she chooses to include only her son in her will, excluding her daughters.
I hope this helps. Thank you for your time and patience!
Regards,
Aadil