Some time ago it was commonplace and accepted practice to use a apostrophe for plurals of foreign nouns which ended in a vowel (Romance languages in particular have a higher incidence of final vowels than English).
There's a longish account of apostrophe use in Wikipedia , which mentions this:
Lynne Truss, author of Eats, Shoots & Leaves, points out that before
the 19th century, it was standard orthography to use the apostrophe to
form a plural of a foreign-sounding word that ended in a vowel (e. g.,
banana’s, folio’s, logo’s, quarto’s, pasta’s, ouzo’s) to clarify
pronunciation. Truss says this usage is no longer considered proper in
Since menu is French in origin, it does fit into the above category.