I believe it's because she is afraid to speak English. She only knows about eight words.
Maybe Mamacita doesn't come out because she is too fat.
I think its because of the three flights of stairs.
"Whatever her reasons, whether she is fat, or can't climb the stairs, or is afraid of English, she won't come down. She sits all day by the window and plays the Spanish radio show and sings all the homesick songs about her country in a voice that sounds like a seagull... She still sighs for her pink house,and then I think she cries." (Cisneros 77)
THIS IS HOME. Here I am. Speak English. Jesus Christ