Answer:
The underlined prepositional phrase "to the front door" is used in the sentence as an adverbial phrase
Step-by-step explanation:
This example is following one of the structures to make an adverbial phrase, which starts with a preposition (in this case "to") the phrase together can be considered an adverb of place, the other three options are not correct because they require different elements in the structure to be considered that kind of phrase.