My father had told me that back before house number were common houses had names. The address on Roberts passport my father believed described the house as "the crest of the hill on Ridge Rd".
I checked the Whitneyville pages of the New Haven County census, and it does appear that the enumerator was in that area during the month of January. According to the passenger lists you found Robert didn't start his voyage home until the last week of February.
I'm intending to go page by page looking for some sign of the family or any of the neighbors I found in the city directory.
I don't think the country club's address would be near their house even back in 1920. Today the main entrance is several blocks away from where I would expect to find the family home in 1920.
Ridge Rd in Hamden, which is where I first was looking, is located in New Haven, Ward 12, district 504 starting on Pg 10A. A few of their neighbors appear but only because I knew who I was looking for. The index lists Jepson as "Yepson". I don't have my notebook in front of me so I can't give other examples right now of the index not matching the written page, but I can later report what I saw.
Hartford Turnpike, Whitneyville, which is the second place I would think to find them is in the Hamden Ward, District 263, and starts on pg 13A.
The pages I have had time to browse so far appear to mostly be along Whitney Ave.
I'm wondering if perhaps while Robert was out of the country the family stayed with friends or relatives. As I don't know if James was still living at home with his parents I don't know if I should expect to find him living somewhere, and perhaps his mum and sisters stayed with him while Robert was away?? I'm new to this research so I'm sorry if I'm asking the wrong questions.
Thanks again for you help. I intend to keep plugging away at this mystery until I can come to an answer.