my grandfather had a DDA alloted plot in 1981 for 7082 rupees . On which he done construction 1982 and i have no proof of construction except naksha. He expired in 1997 and all the legal heirs transfers their share to her mother name in 2011 i.e my grandmother .Now she sell this property for 42 lakh rupees in 2011 and buys a flat for 15lakh 60 thousand rupees in her name and she wishes to buy another residential property of 22 lakh .please suggest her tax liability.