I'll toss my 2 pennies in.
2 people...I don't care how good of a grappler you are, you're going to get stomped. We saw good examples of this with two fight quest episodes...the Krav Maga and Kajukenbo. We all saw what happened. That being said, my first concern would be doing my best to get back to my feet.
Against 1 person...while grappling is certainly a must IMO, to have inyour toolbox, I tend to think that sometimes alot of people think that it means that its still ok to go to the ground. Now, going on the situation that was presented, I would say that an offensive guard, rather than a defensive one, would be the way to go. If you're down, attempt to use your knees as part of your defense. In other words, keep them between you and your opponent. Another method would be to kick at your opponent, in an attempt to keep him back. Are you going to get kicked by him? Well, anythings a possibility.
If you do fully apply the guard, don't turn it into a cuddle match. Why hold him here, doing nothing else? Paul Vunak brings up some great points in
this clip, which was posted on this forum. Goes right back to my comment on the offensive guard.
I'm sure some will say that the thought of biting someone is gross. Well, yes it is, but...if its a matter of me getting my rear kicked, or having a chance to survive, gross or not, I'm taking that chance.
If the situation were reversed, and I was in the guard, same thing. We see G&P (ground and pound) work with success in the ring, so why not do the same thing in the street? The groin is wide open for shots, so take advantage of it. Once its broken, escape.