Which colors combination are better for the bottom navigation bar, while in expanded state, taking in consideration the user experience:
I always say that contrast is the way to go in any sort of long, text-filled thing. However, in your case I'm not sure if one column should be highlighted over another in the section you're asking about.
Before you make your decision, ask yourself if one category or column is more important than the rest or if it would be more useful to the user for it to stand out.
While adding color is a great way to break up a dull page, you shouldn't just add color because it looks good (especially when we're talking about nav.). So to answer your question (keeping user experience in mind) I have questions you should ask yourself before deciding.
Once you've answered these questions, you'll know which color scheme you should use.