Dare Demo = Whoever / Anybody
Itsu Demo = Whenever / Anytime
Doko Demo = Wherever / Anywhere
Nan Demo = Whatever / Anything

Examples
Q : What do you like in sports? – Supo-tsu wa nani ga suki desu ka?
A : I like anything in sports – Supo-tsu wa nan demo suki desu

Q : Where do you like to go this Saturday? – Kondo no doyōbi, doko e ikimashō ka?
A : Anywhere will do – Doko demo ii desu

Q : When do you want to go to the sea? – Itsu, umi e ikimashō ka?
A : Anytime will do – Istu demo ii desu

Q : Who would you choose? – Dare ga (erabu)erabimasu ka?
A : Anybody – Dare demo ii desu
Meaning : Supo-tsu (Sports in Katakana), Suki (Like), Kondo (This “occassion” / This Time), Doyōbi (Saturday),Umi (Sea), Erabu (Choose)