Share of son in a gifted property

Sir, My mother after the death of my father purchased a piece of land from my father's money and after obtaining NOC from my elder brother and younger sister gifted the plot to me which was duly registered in the Registrar's office in 1987. My mother expired in 2005. I got the loan sanctioned from my office to construct the house which I completed in 1988. After living for 19 years in the house I sold this property in 2007. I purchased a kothi flat in 2007 and got it registered in my and my wife's name (50% share basis) My 39 years son who is married is demanding 50% of the share of the property stating that it is a inherited property from Dadi and he has claim over it. I want to know Since my mother gifted me the plot and I became sole owner and got the plot registered in my name subsequently I sold and bought Kothi Floor, has my son got any claim under the law in present property. Thanks, Arun Kumar