Do compound subjects like "everyone ... and everyone..." take singular or plural verb agreement?

Here are the examples of compound subjects:

Everything on the bed and everything in the closet was organised in under an hour.
Everybody who witnessed the shooting and everybody in the room were interviewed.
Anyone on the soccer team and anybody on the basketball team was eligible for the scholarship.

Should I also use was instead of were in the second example? Or the first and the third examples are incorrect that I should use were instead of was.

Solution 1:

There are sources that tell us to use singular agreement in these circumstances:

• 13. Everything on the bed and everything in the closet was organized in under an hour.
  15. Anyone on the soccer team and anybody on the basketball team is eligible for the scholarship.

  ("15 Sentences Using Compound Subjects and Compound Verbs", Your Dictionary)

• When the parts of a compound subject are joined by "and" but the subject is modified by the words "each" or "every", the subject takes a singular verb, not a plural verb

  ("Compound Subjects and Verb Number", by Peter Sokolowski. Ask the Editor. Merriam-Webster's Learner's Dictionary. Monday July 26th 2010)

• focus an eye on these compound subjects followed by singular verbs, all of which are correct:

  • Everything in the cupboard and everything on the table was smashed.
  • Everybody favoring the plan and everybody leaning toward it were interviewed.
  • Nobody in my house and nobody on my street has been robbed.
  • Anyone who has read the book and anybody who has even heard of its ideas agrees with the author.

  ("What Are Compound Subjects in English Grammar?", by Richard Nordquist. ThoughtCo. Updated January 26, 2018)

Normally a subject made up of more than one element takes a plural verb ("The President and Congress are at loggerheads"), although occasionally, when the elements add up to the same idea, the verb is singular ("The wear and tear on the car was tremendous"). But focus an eye on these compound subjects followed by singular verbs, all of which are correct:

• Everything in the cupboard and everything on the table was smashed.
• Everybody favoring the plan and everybody leaning toward it was interviewed.
• Nobody in my house and nobody on my street has been robbed.
• Anyone who has read the book and anybody who has even heard of its ideas agrees with the author.

Unlike subjects joined by 'and,' the very role of 'or' and 'nor' is to separate, to tell us that it's not both things, but one thing or the other that the verb applies to. So the rule is: Subjects joined by or or nor are not considered as a group, and the verb's person and number should agree with those of the subject's individual parts. There are three possible scenarios here. If both parts are singular, as in the subject Mary or Donna, then the verb is singular. If they're both plural, as in the subject Neither the girls nor the boys, the verb is plural. And in really tricky sentences where you have one of each, such as Either Tony or his daughters, the verb should agree with whatever part of the subject it's closest to in the sentence; for example, either Tony or his daughters are or either the daughters or their father is.

(Ann Batko, When Bad Grammar Happens to Good People. Career Press, 2004)