I personally believe that the occupants of B-78 were Edgar Joseph Meyer and his wife Leila Meyer.
(Sorry, I shifted your quote to
this more relevant thread and noted that we have discussed this before!)
May I ask what makes you think that? Of course, the Meyer's cabin allocation is also not certain. I accept that it was possible, but if, as I believe, the Spencers asked to change their cabin
after coming on board with the
Titanic, which would only have been possible if one of them, B-76 or B78, was unoccupied at the time. As fellow
First Class passengers, the Meyers would have also had cabins allocated to them.
Of course, one can speculate that the two couples, both from New York and both boarding in Cherbourg, could have
simply exchanged their cabins for mutual convenience. But I thought that sort of thing was uncommon in stuffy upper-circles of those days, specially with the Meyers being a whole generation younger than the Spencers. Also, as far I can see from BB's
deckplans, B-76 and B-78 are similar in terms of amenities (but might have differed in style).
I have doubts about B-78 being occupied by the Meyers for other reasons.
After he had seen to Guggenheim and Giglio, I made it that it was around 12:30 am that Etches banged on the door of B-78 calling out to its occupants. Allowing some 2 minutes for that strange exchange (which he would have had absolutely no reason to make-up), Etches would have just had enough time to do the few other things he said, including going to the boat deck to help with the completion of loading Lifeboat #7 (where I think he reported seeing McElroy) and then on to help with Lifeboat #5, into which he was ordered by Murdoch as it was lowered at 12:48 am or so. Comparing this with Leila Meyer's later account of her final parting from husband Edgar Meyer, it seems that they were near Lifeboat #6 well on time and she rescued on it as it lowered at 01:10 am. I would have thought for a couple to be asking rather silly questions of their steward through a locked door at 12:30 am to then dress warmly, put on life vests and arrive on the boat deck in less than 30 minutes seems unlikely; possible, but IMO it does not fit. More than anything else, they were a 'proper' married couple and so why the hesitancy in opening the door to urgent banging and calling out? Or the reason for Leila Meyer not mentioning the incident later?
Also, even if Etches was not actually serving B-76 or B-78, working in the vicinity for 4 days (since Cherbourg), he would have known from his colleague who the occupants were and would have said so at the inquiry.