Mother or mommy will be always one of the most important words out of respect for the person who
gave birth to you and guided you in your early life.
So in that perspective "mommy" will stay an important
word in her life, but later she will more likely use words
like mom or mother. In South-Africa it was funny to
hear a 33 years old mother of two kids (my sister)
and a 34 year old guy (myself) saying "Mamma"
duch for "Mommy" or Mother to our mother.
Because we see eachother so rarely we do not use that
word much. You don't use it in phonecalls with your mother. Now I think of it I use the word Dad less than mother. In families the mother is the central person.

As a kid it was funny to hear my mother speak Polish to her mother in Poz�an on the phone, and using the word Mammo. Because the connection was very bad she spoke very loudly. Mammo, Mammo, Mammo, .....
are you there (in Polish ofcourse).
I first heard Polish due to my mothers phone calls with
Poland and America.