I hope everyone_______learned something from this.

Had

Have

Has

Has to

I hope everyone has learned something from this.

Explanation:

To use the correct verb form, we should always follow the rules of subject-verb agreement.
Subject-verb agreement decides whether a subject is singular or plural.
If the subject is considered to be singular then it will take singular verb.
If the subject is considered to be plural, then it will take plural verb.
According to the rules of subject-verb agreement, Indefinite pronouns are singular and they always take singular verb.