NEVER EVER EVER LEAVE YOUR CHILDREN ALONE WITH A JEHOVAHS WITNESS.They see it as an opportunity to pour their poison into their little heads.
Invite your parents round get together as a family. Let your kids see how callous and cruel witlesses are to their own children. /they will soon realise that the cult is based on fear and intimidation.
Sit in the room with them. Dont let your Mom dictate terms to you in your own home. Absolutely do not agree to drop the kids off, and let her ignore you.