because they have a house that is comfortable and not too extravagent. If they were beggars or poor people, they would not have had a house or furniture. I don't think they are nobles because the author would've gave us a luxurious description of their house and furniture. Therefore, I think they are commoners.
Also, I saw a glimpse of the story and it said the husband just got a new job and they were happy to finally be financially stable, so i think they are commoners.
