Who is Mother from Hocus Pocus and what is their importance?

Mother is the name Eugene gives to his mom. She is very much a shadowy figure throughout the book, relegated to basically a supporting status for Father as dutiful and silent wife. Her only real claim to success besides the birth of Eugene is that she lost a lot of weight and went from being obese to in shape. She dies in a tragic accident near Niagara Falls along with Father.