A multi-layered remark. On the surface, it means that he's alone with Teresa:
no servants or guests are left. Politically, it means that he alone clings to
a unifying dream-ideal in the triumph of Separatist elements. That might even
include Teresa, who became a Separatist herself by urging Nostromo to abandon
loyalty to society and "get riches." Philosophically, it restates the
subjectivist theme that all men are fundamentally alone and isolated.