Sri Aurobindo is the full name of Sri Aurobindo and it has a mantric power in it. Sri is not a honorific but the name as it is known in the occult inner worlds.
Mother is a relation that the aspirant or sadhak feels and forms with the Divine Mother. It is not a name. The Mother implies that She does not represent one or other aspect of the Divine Mother but is the Divine Mother in all Her fullness. It is also to differentiate her from the general sense in which the word Mother is often used from one’s physical mother to a woman saint and so on and so forth.
Affectionately,
Alok Da