Income from share of property sale by mothers Mother propery

i have query in followng case

if we any one received share of Income from sale of Property of Mother's Mother Property,

the property is very old May be older than 40-50 years having no purchase record,

now Mothers age is more than 60 years

amount received is RS. 5,00,000

is the total amount will be taxable or what is tax treatment

Please guide in above case

Thanking You