a) Better an open enemy than a false friend.
The meaning of the proverb is that you cannot trust false friends. Someone who is only pretending that he or she is your friend will stand by you only when they can gain something but will leave you when you need then most. On the other hand, when someone is saying he or she is your enemy, at least you know that you will need to avoid them in the future.
b) A friend to all is a friend to none.
The proverb makes us aware that people who try to please everybody are in fact none's real friend. A real friend will side with you when you are arguing with somebody else. If your friend is trying to be friends with your enemy, than he or she is neither your friend and is not your enemy's friend either.
