I know that Lani means "Heaven" in Hawaiian and it is used as an element in many names. I could not confirm the meaning of Oka through my own research, however. The meanings I found for Oka (as a word) are "crumb, grounds, remnents." For 'Oka I found the meaning "oak (tree/wood.)" To find those meanings I used http://wehewehe.org/ . While the dictionary listed Lani as a name element it did not list Oka or 'Oka as one.
I'm not an expert but maybe this will help you.
----- Hawkeye: "Who would name their kid BJ?!" BJ: "My mother, Bea Hunicutt, and my father, Jay Hunicutt."