A 'score' means 'twenty', so two score is 40. Some is used here to mean 'approximately'. So the sentence means he invited somewhere between 20 and 40 families.
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khoffBy the way, I if you're talking about the novel "Moby " and not the musician called "Moby", please use the full title. Very few of us are on a first-name basis with "Moby ."This is probably a site-censorship issue.