Question

Either the man or his friend …………coming.

is

are

were​

Answer 1

Either the man or his friend is coming.

Answer 2

Is

Usage:

Is: "Is" used in the present tense and verbs in the singular third person (such as "he," "Smith," or "Jake").

Are: If the word noun is plural or has more than one noun, then "a" is used.

Were: It is used for both second person in the past tense and third person plural of the past tense.

Therefore, the word "is" is used in this sentence. And the sentence will be: Either the man or his friend is coming.