Is Lois' the singular possessive of Lois?

Answer 1

There are two accepted forms for possessive singular nouns ending in s:

Add an apostrophe (') after the existing s at the end of the word: Lois'

Add an apostrophe s ('s) after the existing s at the end of the word: Lois's

Examples:

I met Lois' mother at the meeting.

I met Lois's mother at the meeting.

Note: The -s's is the most commonly used form, but if you are a student, use the form that is preferred by your teacher.

Answer 2

No. The correct spelling of "Lois's" would be "Lois' ".

The 's denotes possession. If you are talking about something that belongs to Lois, Lois's is correct.