Mother Teresa has been dead for years so she has no income. When she was alive she very humble and poor. Her travels may have been funded by the Catholic Church and catholic people. But, much as Christ did, she depended on the generosity of strangers to eat and have a roof over her head. As a nun im sure she most often stayed in and ate in convents and nunnerys in the areas she traveled to whenever possible.
Pretty much all that Mother Teresa had was down to donations and handouts. Even some of the space she built her homes and hospices were donated by individuals and states. There cannot be found a source suggesting she had other sources of income.