Who is datu zula is he the father of rajah humabon?

No, he is not.

Raja Zula is one of the chieftains of Matan the other one is Datu Çilapulapu (Lapu-lapu), they rulledat the same as Rajah Humabon.

Rajah Humabon's name is Sri Hamabar, he is 3rd rajah of Singhapala of the Rajanate of Zubu (Cebu). He the son of Sri Bantug and nephew of Sri Parang the limp.