(Great?) grandpa and grandma stopped driving oh, gosh, who knows how long ago! These cars look to have not moved in quite awhile; that’s substantially more than just moss growing round the tires. The imperial might be a ’67; I didn’t get out to check for side marker lights, but I think that emblem in the middle of the full-width taillight is the ’68 style.
There’s a light on in the house. I bet it’s a bare bulb on a timer—the old motorised type, from a long-defunct company like Lafayette.