A very tough situation indeed. I would take the middle ground - share some resources but send them on their way. This really is a potentially no win situation.

Hopefully a little charity will go a long way....

I have all three and like to shoot them all. From a purely cost perspective the 9mm gets my vote. I actually prefer to shoot the .45, though they are all fun. If I were in a pinch I would pull out .40 with hollow points and an in between magazine capacity to the 9mm and .45. With three, twelve round magazines I feel pretty well armed. Hopefully I will never have to put it to the test...