A bass trap is a passive device that can only dissipate acoustic energy from a room. As such it can never eliminate a null in room response since it cannot add energy into the room. However, if you have two bass peaks it's possible that room traps can eliminate the peaks to generate smooth bass response. But in that case you didn't really have a bass null, but two bass peaks.
If you measure room response in narrow enough bands you'll typically find any number of very deep and very narrow nulls. As a practical matter they cannot be eliminated. Fortunately, they usually aren't a noticeable problem. Broad band nulls are a major problem. Repositioning the speaker and/or listener is the best way to address that type of problem.
