I don't want grandma to see the kids
Is there a reason that she does not need to be around the kids?
She's dangerous and creepy
You should try to have your kids see their grandma. She will probably not be around long, so let her spend time with them since she's family.
They get too attached and I don't want that.
That is a big part of childhood, seeing your grandparents. You should do what you can to let you kids be around her while she is still alive.