Gift to Grand mother

sir,
I have received gift from my Nana (my mother's father) RS 1 Crore by gift deed and now for tax planning I want to give 75 LACS to my grandmother (my father mother) as she is senior citizen and income in her hand up to 5 LACS is tax-free

she is 81 years and she wants to make will and in will she mention that after she passes away I will get entire amount along with interest earned in particular bank account no to me in which gift amount is deposited through cheque

I am filing return and my income falls up to 3.5 lacs I am 30 years old

Regards
Ragnesh Prajapati