Do you think he will do me a favor?

你认为他会帮我一个忙吗？

It's very unlikely , but he (   ) be prepared to help you.

这非常不太可能，但是他也许愿意帮助你.

A.might

B.may

C.would

答案给了A，我没能理解如果用C的话 该怎么翻译。

还有就是be prepared是什么意思？

感谢专家老师！

回答如下：

(1)主语+might be unlikely to do sth 主语也许不太可能做某事.（might表示主语对后面动作发生概率较低推测）

(2)主语+would be unlikely to do sth 主语不太可能会做某事.（would表示较高推测）

(1)unlikely adj. 未必的，不一定有把握的；不太可能的；不可能发生的；不像是真的 ;未必会发生的

A military coup seems unlikely.

看起来不太可能会发生军事政变。

As with many technological revolutions, you are unlikely to be aware of it.

就像诸多的技术革命一样，你可能不太会注意到它。

It's now unlikely that future parliaments will bring back the death penalty.

现在看来，将来议会不太可能恢复死刑。

In the unlikely event of anybody phoning, could you just scribble a message down? 

虽然可能性极小，但如果有人打来电话，你能不能随手把留言记下来？

短语主语+be prepared to do sth

(1)主语愿意做某事

Are you prepared to take industrial action?

你们愿意采取劳工行动吗？

Members of the KGB service were only prepared to take orders from the President. 

克格勃的成员只接受总统的命令。

(2)主语准备好做某事

Police are prepared for large numbers of demonstrators

警方已经为应对大量示威者做好了准备。

I'm well prepared for a 12-round fight. 

我已经为迎战12个回合的拳击比赛作好了充分准备。

综合以上，得出结论，概率较低，可能未必做某事.