Options A and C:
A 'rabble' is 'a disorderly crowd, a group of ordinary people, regarded as socially inferior or uncivilized'.
A 'mob' is 'a large crowd of people, especially one that is disorderly and intent on causing violence'.
The former means the same as the given phrase, as it refers to the type of people (those in a rowdy scene) whereas the latter 'mob' does not imply those qualities (dirty, unkempt, uncivilized people).
Hence the former is suitable to substitute for the phrase and option C is correct, A is wrong.
Option B: A 'crowd' is a large number of people gathered in a disorderly way'. It can be a group turning up for a concert or for an election rally. It does not refer to 'a rowdy scene' in particular.
Option D: 'Congregation' is 'a group of people assembled for religious worship'.
These words do not mean the same as the given phrase and hence cannot substitute for it.
So, options B and D are wrong.