My mom unknowingly used 2 pcs of bread from a loaf that had black mold. made my daughter a grilled cheese sand(no mold)daughter ate 1/4 of it. toxic?

Usually not : Most molds are harmless, but some are dangerous. Some contain mycotoxins. The USDA has a nice chart about how to deal with various foods that are moldy. Check it out for all the details. It breaks down into the two obvious options – http://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/safe-food-handling/molds-on-food-are-they-dangerous_/