I thought it was the house. After all, the mother's secret room was there. Why would that be the store? Wikipedia says the store. Anyone can edit Wikipedia which means Wikipedia can be wrong, but if it is wrong, this also means anyone can fix it.
shareit was the house and store together as I believe, that was not uncommon for years for people to live above their store or adjacent.
shareIt was the store that burned. The room above the store was the mothers space. They lived across the road with the uncle (think he was an uncle). Would make sense that if living with their uncle she probably didn't have a "private place" in that home and made it in the room above the store.
shareThe room above the store was the mother's personal space ... likely an office as well.
The family lived across the street in another house.