What happened Mia?

Mother, Father, and younger brother teddy
Killed in a car accident
Mia being she only one survivor
Not knowing if she should stay or die 

Not being able to make up her mind
She's like a baby
Being more excited than a child as soon as Adam pulls up
Adam trying to see Mia 
Grandad thinking it's best not to let him

As a 17-year-old
A high school senior
Being the protagonist
Can't decide to stay alive or die 
Rest of her family not surviving