What does she means by ancestral properties?
A legal notice cannot stop you from going ahead with the proposed alienation or transfer of the property held by your parents.
She cannot restrict your father from transacting with his self acquired property.
If she was married before 2005 and if the one property referred to herein above is really ancestral in nature, she is not entitled to a share in it
Therefore ignore her notice and proceed as per your proposed action plans.