Hmm, that is weird! I wonder if it was a former address or business that your family members used because they didn't have a definite new home or maybe a landsmanschaft (Were they Jewish?). Does the 'friend' at that address show up as living somewhere else? I've found some 'friends' who seems to be totally unrelated to my relatives-and found some unexpected relatives as well.

This looks like the right county office to call- http://www.hudsoncountynj.org/dept/registers_office/
There might also be deeds online. I know NJ is slow in the whole online thing with records, but they are getting there!

Also try looking at the phone directories for those years. Many of them go by name AND address. Really helpful!