Final answer:
The corrected sentence is "Mom brought the groceries home, or it could have been Dad," with a change in verb tense and correction of the common error "could of" to "could have."
Step-by-step explanation:
The given sentence should be corrected to say, "Mom brought the groceries home, or it could have been Dad." In addition to fixing the past tense verb form (from "bring" to "brought"), the phrase "could of" is a common error and should be "could have." Also, since the sentence presents two alternative scenarios, a comma is used before the conjunction "or" to separate the clauses.