Libertarianism seems to be arguing, however, that (a) is the correct and proper action.

You don't seem like someone well-acquainted with the relevant literature. If a policy seems obviously correct, and doesn't involve coercing someone else into doing things against their will, then Libertarianism (at least, read as roughly equivalent to Lockean classical liberalism) won't tell you not to do it.

A lot of libertarians are very enthusiastic about charity and philanthropy; they are less enthusiastic about being forced into it at gunpoint.

Is there any point to having this conversation here?

If you think libertarianism argues that a) is the correct and proper action then you don't understand libertarianism. I'm not even sure how you'd arrive at the idea that it does. I'm guessing that you are trying to make some kind of analogy between libertarian attitudes to government and libertarian attitudes to individual interactions but that you are assuming ideas about government that libertarians do not share.

As for the natural disaster scenario, the basis of libertarian ethics is that people should not be compelled to do anything by force. Voluntary charity is perfectly compatible with libertarianism and indeed libertarians often believe that voluntary charity is a much more satisfactory solution to most of the social problems that governments currently take it upon themselves to address.

Libertarianism seems to be arguing, however, that (a) is the correct and proper action.

No, it really doesn't. "Naively optimised self interest" suggests (a) and libertarianism is almost irrelevent to the question. Maybe if the question was "should people be coerced into b independently of any contract (formal or implicit) with the owner?"