I think its LionHead + Fantail ? = Oranda ?

just my theory... what u guys think abt it ? Please let me know.

Yeah, that very well is a possibility. It also could have been two lionheads, because the dorsal not being there is a rather hard to breed for, and even when breeding to dorsalless fish, like ranchu or lionheads, there will always be a big number of offspring with their dorsal fins. Although if I remember right, the fantail came before the lionhead in the whole "goldfish life line".
What also could have happened is that between a bunch of fantail fry there were a few that had the bumpy appearance on their heads, and the Chinese figured that it looks good, so they kept breeding just those fish with the appearing "bumps".

Some say it's a variation of the ryukin

That theory is the most possible IMO, and with each generation, the "bumps" get bigger and thus the wen was born