Legal remedy to recover husband's property from mother in law

As per fact stated above, your mother in law is entitled to 1 share, if she didn't come forward to divide said property among other equal shareholders, you can file a suit for partition along with prayer of cancellation said transaction.

If it is owned by your father in law after his death the property will go to his legal heirs which include your late husband and his wife and other children if any. You can claim as a heir to your late husbands share in that property.

After your husband was bequeathed certain property by your father in law by will, did your husband transfer it to your mother in law by gift? If so, your mother in law's title and ownership cannot be challenged now.