Here is a nice example of a 1948 Bulova Her Excellency B. It is a white 10kt gold filled case and case back with a dot/square white dial with a 12 and 6 hour marker. The movement is a 21J 6BA with an 48 date code. 1948 Bulova Her Excellency "B"
1948 Bulova Her Excellency B
Advert dial is different from the subject watch. Might it be a different variant?
Case wise I agree it matches that of a Her Excellency "B". but it does appear to have a dial from another model as most HE's I can see have a fully numbered dial.
Found this matching advert confiming the watch is part of the Her Excellency Group and the dial is correct for this group. Doesn't state the variant unfortunately.

Ok I can now see that the other examples we have ID'd as the "B" variant all match the subject watch dial. So happy to also ID as the "B" to keep grouped.
1948 Bulova Her Excellency "B"
The "B" is a white version to the "A" with a different dial. Great looking watch imo.
1948 Bulova Her Excellency "B"