* Yo preferiría viajar por carretera y me alojaría en un albergue juvenil.
Explanation:
Because the sentence is narrated in the first person singular describing a future situation, therefore we must take this into account when conjugating the verb prefer that the options show. In this way we will know what is the logical way to conjugate it and that it has concordance with what is being expressed.
preferiría is used for when you would prefer something, while preferirías y preferirían is used for when other people would prefer something, and preferiríamos refers to we, as in we would prefer something. in this case you would prefer to drive so you would use preferiría
