You have not mentioned if your daughter wants the help. It's important that she comes to you and ask for help. Try to find out from her if he has just been verbally abused or if he has been physically abusive as well. This means pushing, shoving, slapping, kicking, throwing things at her or the children. Although very painful for you to listen too and the fear of something terrible happening to your daughter and your grandchildren, it is very important you find time to sit down with your daughter and have a heart-to-heart talk. Let her talk and you listen. If you have experienced any abuse in your life then this is the time to pull the magic out of the bag and relate this to your daughter. If not, then you must learn as much as you can about abusive relationship, the law and how best to protect her.
If your daughter is agreeable and ready to leave her abusive husband, then please contact your Women's Shelters or Women's Centers. If you find them difficult to find just call your local Mental Health in your area and they will give you the phone numbers. Next, you should accompany your daughter to meet with the counsellor at the Women's Center and she will be asked questions. Women's Centers are there to protect and will lead your daughter and yourself in the right direction to get good help (also legal help.) It is very important to seek legal council and there is good help at Transition Houses for Women and Women's Centers. Your daughter and her children will be protected by these agencies. Be prepared yourself to need a little protection because if her husband flies into rages you will be the first one he will come to trying to find out where your daughter is.
God Bless Marcy