Is there a natural Human Right to be able to support a household on one adult income?

No, as things stand there is not. There would be nothing "natural" about it in any case; in nature the stronger or more aggressive tend to prevail. Should a civilized society see to it that everyone at least has what they need to not be homeless, starving or ill ? Yes, personally I believe that it should. But in some countries, based upon the cost of living, it would not be possible for some households to subsist on one person’s earnings (depending on the size of the household and amount of said earnings) without help. That help should indeed be available.

"From each according to his ability, to each according to his needs".