Question

why was it hard for the author to believe that his grandmother was ones young and pretty?

Answer 1

Here is your answer :-

Because the author khushwant Singh only saw his motger old . He had been seeing his mother old since 20 years .
So it is hard for the author to believe that his grandmother was ones young and pretty .

Answer 2

Reason why it is hard for the author to believe in young and pretty look of his grandmother in her childhood days:

It was hard for the author to believe that his grandmother was once young and pretty because he has never seen her childhood and adulthood photos. As the author was growing up, he saw his grandmother during her old age time and he believed that his grandmother appearance which he sees with help of his own eyes are true and the appearance described by her in stories are deceptive.