How to invest my father's retirement fund.

My father is retiring next year and gonna get 50-60lakhs ig. Im very new here but I want to learn more. Where can I park these fund so we can get good returns. I thought to invest in fd but heard something like there will be 30% tax cut while taking. Should I invest these on land. Or should I open a demat acc on my father's name to invest for long term on stocks and bonds?? What could be the ideal thing u would have done if u were in my place. We already have a house and everything is sorted for now. But my sister gonna get married in 3-4 years. Where Ig we need to spend 10-15 lakhs. Pls help me.