Roast chicken dinner always goes down
well . Jewish chicken soup, if you have
never tried it ..it's ace .Sure your friends
will enjoy what ever you cook , have a good
time .
You need to know if they keep to a Kosher diet - altho it would have been polite of them to tell you when they accepted the invitation. Your best bet is to serve vegetarian food or fish (no shellfish).
Also don't serve any shell fish, monk fish. If the people are observant, and if you want to be on the safe side, it may be best to serve vegetarian food, check that any cheese you may serve is vegetarian too!