“all of my kin are” “each of my kin is” (they mean the same)

The second sentence is correct. However, it sounds unnatural. One natural way to phrase the idea is "I have no living relatives." 1) "Kin" and "relatives" are synonyms, but "kin" is rare and "relative" is common. 2) "Deceased" is a formal word that is used in official and legal contexts. The most direct word is "dead." The most common term nowadays in US conversation is "have passed." 3) "Living relatives" is a standard phrase. Perhaps it seems nicer to say "none are living" than "all are dead."

'kin' is considered a plural noun therefore the second option is correct.