Hello Erato and Milliepede. Regarding which Crystal City it is, I can only assume this actually refers to the area now falling just south of Washington. I will try and briefly explain why I think it is that one.
I already know that the Hood family had an earlier connection with Canada (which I am trying to explore on another board on Rootschat). In addition, again with help off here, it seems that soon after Franklin and Mary Jane (also referred to as Jennie) were married in 1884 in Scarborough, UK, they travelled over to New York. According to the ship manifest, they were destined for Baltimore which I believe is not very far away from Washington. It would seem that they only stayed in North America for a few years because they are back in England for the 1891 census, with Nellie/Ellen. My biggest hope had been trying to find a Hood family in Baltimore in the 1890 census but unfortunately most of those records have been lost, so hence I am now trying to find Ellen's birth's records.
Hope this ramble all makes sense!