Bogis' Problem

[Lex]

In this last quest of frogmen trio I have two options how I would like to complete the quest:
A. put the flag of eldest brother on two houses of younger brothers
B. attack eldest brother and put king's flag on all three houses

Choosing option A gives quest reward and additional troops/items to buy in frogmen's houses.
Choosing option B gives quest reward and.. nothing else?

Yes, option B gives also some experience for fight with eldest brother but is this the only one additional gain?