is bitkingdom.org legit?
A quick websearch found me a review on BehindMLM. The site indicates that BitKingdom was a multi-layer marketing scheme. Unless your grandfather happened to be one of the first investors and actually cashed out, the funds are probably lost.
Disclaimer: I'm only familiar in passing with BehindMLM, but they had a lot of useful background information on BitClub and OneCoin in the past. I have not further verified this initial take.