Sometimes singular and plural pronouns and apostrophes can leave you feeling like you’re swimming in a turbulent ocean. Such is the case with everyone’s vs. everyones’ vs. everyones.
To begin, we should know the difference between everyone and every one. Everyone is the equivalent of everybody and refers to all members of a group, as in The street widening will affect everyone living on the block. In contrast, every one means each individual in a group, as in I will send thank you notes to every one who gave me a wedding gift. To help remember the difference, for emphasis you always can add each (one person) to a sentence containing every one, as in The bride danced with each and every one of the male guests at the reception.
Given this, we can can conclude that everyone is a singular pronoun. That is, it refers to a collection of people or a group. Just as the word group is singular (groups is plural), so everyone also is singular.
So to show possession, the apostrophe should go between the final e and s as in everyone’s. The other two are incorrect, first because everyones’ implies everyone is plural (which it isn’t) and everyones isn’t an actual possessive pronoun like his or hers.
Unfortunately, this grammar rule isn’t universal. In Britain, sometimes everyone and everybody are considered plural pronouns. The recommendation here assumes you’ve made landfall on the American side of the Atlantic.
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My name is Rob Bignell. I’m an affordable, professional editor who runs Inventing Reality Editing Service, which meets the manuscript needs of writers both new and published. I also offer a variety of self-publishing services. During the past decade, I’ve helped more than 300 novelists and nonfiction authors obtain their publishing dreams at reasonable prices. I’m also the author of the 7 Minutes a Day… writing guidebooks, four nonfiction hiking guidebook series, and the literary novel Windmill. Several of my short stories in the literary and science fiction genres also have been published.