Surely it's always 'each others' without an apostrophe. 'Each other' is a (reciprocal) pronoun, so in its possessive case it becomes a possessive pronoun. None of the others: its, his, hers, yours, whose etc has an apostrophe. Adding one is generally seen as a sign of poor literacy.

Surely it's always each others
Each other is a (reciprocal) pronoun, so in its possessive case it becomes a possessive pronoun. 
None of the others: its, his, hers, yours, whose etc has an apostrophe. Adding one is generally seen as a sign of poor literacy.