Mbone is the title of a song performed by Daddy Owen, but no mention of who Mbona is.
Karibu.- means how comeThe above answer is entirely wrong. Karibu means "come closer," and is often translated into English (often incorrectly) as "welcome." How come in English means simply "why?" often with an edge of doubt to it.How come? = kwa nini? (why?) in the simplest sense of the question. Swahili has another form, mbona? which has a bit of an edge to it, like "How come?" Mbona umechelewa? How come you're late?
niniThis is a wrong answer. Nini is an interrogative pronoun meaning "what." There are two ways to ask "Why?" The standard is kwa nini (literally, for what). Also commonly used is mbona, which means "why" but usually implies impatience or criticism: mbona umefanya hivi? means "why have you done this?" usually implying that you should not have done it or that the speaker is unhappy you did it.ADDITIONS:Mbona = lit. whyKwa nini = loosely translates to "for what?"Kwa sababu gani? = loosely translates to "for what reason?"