"He always lives alone and helps the farmers."
Translation:Er wohnt immer alleine und hilft den Bauern.
At the same time, Reverso shows "alleine" (informal) as a variant of "allein" (adj). But not the "allein" (adv).
Late answer, but the way I understand it is that 'und' creates a new sentence. So it could be seen as 'Er wohnt immer alleine. Er hilft den Bauern.' The 'und' connects the two and the second 'er' can be dropped because the sentences are connected (so the verb is still in the second place, it's just an invisble 'er').