What was the symbolism of ashes in Angela's Ashes?

Angela's only comfort, as she would say herself, were her
Woodbine cigarettes, which she smoked with her husband (when he was home) while they sat
by the fire looking at the firewood consume itself until it turned into ashes. That
would be one of the symbols of the ashes: The sole comfort in Angela's weary and tired ,
and sacrificed life. Also, in the end of the book 'Tis which is the
continuation of the story of Frank McCourt, he mention's how Angela's Ashes (after her
death) will basically be inmortal for she had given Frank the opportunity to live the
life he lived.

So, concisely, Angela was literally "burnt"
by her husband, by her limitations, and by the want of a better life for her children.
She literally got to a point where she thought she might as well give it all up. She saw
a few of her children die, she suffered through poverty and hunger, she was in an
unstable marriage, she suffered degradation, and she had to fight through it all as best
as she could. When Frank finally made it somewhat in life, he noticed how the wear and
tear of years had left a huge burnt soul out of Angela. That could also be the meaning
of the word "ashes". - What was left of her.