Yes. But the meaning of -ék can be more broad than just family. It's more like "...and the rest of the group." Context would decide whether that means "Janos and his family" or "Janos and those guys" or "Janos and his buddies" or whatever precisely. (Jánosék is almost exactly what people - with bad grammar - would have referred to as "Janos an' them" where I grew up.)
"Yous" occurs in some very, er, special accents of American English as well - namely those of a few very special cities in New England. As for the rest of us Americans, if we want to use to a grammatically incorrect plural form of "you", we say "y'all", a contraction of "you all". (And if you want to get really grammatically incorrect, you can even say "all y'all" - "all you all"!)
"Jánosék" doesn't have an English translation. "János and his friends" and "János and his family" are both possibilities, but they're both too specific. When translating family letters on genealogy forums, I usually use "János & Co.", and then explain that it's like "the Smiths", but with given names. So for Duolingo's purposes, just use a surname: "Hol vannak Tóthék?" = "Where are the Tóths?".