"If your house were on fire, what single object would you take with you?"

 This is a question that becomes difficult to answer largely through lack of context.

Let's assume I'm trying to pick an object to take OUT of the house.  Let's assume all people and pets are already out.  Let's assume I'm clothed, and I have my wallet/ID and that someone has already called the fire department.  Let's assume that the fire itself does not count as an object that can be removed, safely, by me (otherwise, that's what I'd take out of the house).  Oh, wait, let's assume it's a house, not an apartment.  And that my car is over yonder, not in the house's garage.

This leaves the original intent of the question intact: what irreplaceable thing do I possess that I would most want to save.  Probably my hard drive.  In fact, most people seem to pick binary data, rather than objects.  But I also have old-fashioned photos and even (gasp) written letters.  And books.  Does "book collection" count as one thing?  I couldn't carry it out very fast, that's for sure.  I bet my housefire would hold steady at 451 degrees for a long, long time.