1). If you have acidic conditions, you don’t need the base B:, erase it immediately, because it is a serious mistake. Just continue by drawing an acidic dehydration and that’s all.
2). Try a retro-synthesis and go back:
2-Cyclohexenone ← 3-hydroxy-cyclohexanone ← ? (= a six member aliphatic aldehyde containing a ketone group at the end.)
3). Ignore the methoxide catalysis for the moment. But for your own and further information, this reaction involves a cyclization step that has a higher activation energy and therefore, strong catalysis is needed. On the other hand, strong basic conditions avoid the simultaneous double aldolization of a ketone by an aldehyde, contrary to strong acidic conditions that favor it.