Mable "Madea" R. Simmons is a character based on his mother and grandmother, played by Tyler Perry. She is an aggressive woman who will argue with anyone. This is reflected in her tag line, "Purnch You in the Face!" However, she is also part of a large family, with many children and grandchildren. Her name is spelled variously as "Mabel" and "Mable," probably in order to confuse government authorities and others when applying for jobs, getting credit cards, etc.
"Madea" or "Madear" is a typical Southern name for a grandmother. The term is a shortened form of "Mother Dear."