OK, class, let’s review: apostrophes indicate possession, not plurality. Therefore when you write, “Wilson’s,” you are not referring to a group of Wilson family members; you are referring to something that belongs to someone named “Wilson.”
Let us consider an example in which the writer intends to say that members of the Wilson family are accompanying his own family:
The Wilson’s are coming with us. (incorrect)
The Wilsons are coming with us. (correct)
If you are writing in the form of first sentence, stop it. Right now!
And while I’m at it, regardless of how strange it may sound, add es to pluralize surnames ending in s (for that matter, x or z, too):
The Collins’ invited us to dinner. (incorrect)
The Collinses invited us to dinner. (correct)
As you can imagine, having a last name ending in s myself, I have suffered this transgression many a time.
Back to apostrophes. Yes, to pluralize a single letter, add ’s (e.g., p’s & q’s), but I haven’t seen any surnames consisting of just one letter. (Well, except for Mr. T, but there’s just one of him.)
Your reading assignments for this evening: