In case you happen to witness a family quarrel in your immediate neighbourhood, you would:

The correct choice is: inform other neighbours and try to intervene

A responsible neighbour gets help from other neighbours and tries to calm the situation peacefully. Ignoring it shows indifference, shouting makes it worse, and calling the police at once is an over-reaction to an ordinary quarrel.

Hence the best response is ‘inform other neighbours and try to intervene’.