Answer:
The verb in the passage that is in the subjunctive mood is: drive.
Step-by-step explanation:
In English, the subjunctive mood is used to express wishes, demands, suggestions, possibilities or hypothetical situations. There are a few verbs that will attract, so to speak, a subjunctive verb: demand, insist, and suggest. That is precisely what happens in the passage we are analyzing here. In the sentence, "We suggested that Brenda drive to Grandfather's. . ." we have "suggested" attracting the verb "drive" in the subjunctive mood. Notice that it would be wrong to say "drives" in this case.