Once she filed for I'485 her visa is no longer valid. Her status is "pending until the adjustment of status is adjudicated" so she will not accumulate overstay even after her i-94 expires.
She can no longer use her tourist visa, she MUST stay in the country until she receives her green card and if she MUST travel outside of the US, then she needs to have an approved advance parole document (i-131)
