I was in a situation like this years ago where someone needed some money and I was asked to join a group of contributors. I'm glad I did it because I think it brings good karma. I know it's unrelated, but a few years later I got a job chairing a semi-state board - something I never dreamed I could do. It's always an honour and a pleasure to help out a friend in need. Actually, who is your friend, B? I might know him.
Perhaps it is a sign of the times, but I was thinking similar thoughts.
On the main topic - never a lender or borrower be. A few twenties here or there on a night out is one thing but clubbing together to "bail" out an acquaintence is not something I would willingly subscribe to. Perhaps I'm not a good friend ... but then my circle of friends is such that we don't put each other in those types of situations.
Lord if B is in a bad way for money and you cannot give it directly why not go through A as long as A will hand it over what difference does it make about the great wealth in the future. If you know the money is not for betting, drinking, drugs, fleeing the country or to fund an alien invasion give it! For B to admit to A that he/she needs money things must be bad. If you gave it to a charity you would not know the people involved you have a chance here to help a person with whom you and your husband have a personal connection.
Lets hope the economic bubble never bursts and we have to rely on "friends" with cap in hand.