Which scenario - the husband with a family or the single guy with nothing to lose? Two vastly different moral scenarios.Start with the OP scenario:
OP Said: "Hidden in a field above my bunker, I spot a woman and child being pursued by a gang of men who, if they capture them (which seems imminent), will rape, murder, and eat them".
He makes no mention of, and says nothing of concern for any wife or children, so go with "the single guy with nothing to lose" (except his life) first. Who said anything about a wife and children any way?
However, I would argue that even if there was a "lone wolf" single guy out there who came across a distressed lady/child, it depends on the # of criminals and his skills on whether he should risk his life to help. I said "should" because one is not allowed to put themselves in danger of death, except for extreme circumstances. If you enter a fight you know you can't win (assuming you don't have a duty to be in the fight), then I think that would be morally wrong. False courage is not a virtue and God does not require the impossible.
Make the number of criminals, "the gang", 5 or 6.
Certainly, there is much left out of the scenario. Are the woman/child faithful Catholics? Is the guy in the bunker married with children? If any, what weapons does he / the gang have? Are they being chased in a subdivision, desert, woods or ? How many are chasing them? and on and on.
He did not ask "what to do?", he asked, "What is the Catholic thing to do?" Which of course, obviously it'd be plain stupid to stand in front of a tank, or to think it worth trying to help if 50 raving, drooling gang members are almost on her and the child.
For me, I imagined it to be at least a somewhat workable scenario. In which case, the Catholic should at least do something to help them escape - because *that* would be the Catholic thing to do.