I suggest spending time in the start with a small toy or sponge ball in a "Getting to Know You" exercise. I always find that this works wonders and is a great ice breaker. Probably the mothers will have some friends in the class but the majority of them will not know all the other mothers so it's a great way for them to practice English while having fun and making new friends.
I suggest (depending on how much space you have) arranging the mothers into a circle and have them throw a sponge ball to each other saying - "My name is ______, what's your name?" Best to bring a few sponge balls in case you have a big class and have to break them up into groups. Then after a few minutes of this, change the target language to, "Her name is _______, my name is _____, what's your name?" and so on and so forth. And it doesn't have to be in a circle.
If you don't have a lot of space it can be in a straight line like Chinese Whispers passing the ball to the person beside you, down the line to the end and the group (break them in teams A and B) and the team that goes through the target language the fastest is the winner. I know that they are mothers but they act like kids (especially in Korea) so have some prizes as well for the winners.
Best of luck
-livinginkorea