She can NOT "get his tax return from his job"*. What she can get is the Earned Income Credit (EIC), a generous government hand out for being able to claim a child, 17 is too old for the other tax hand out, the Child Tax Credit. He cannot claim the EIC on his own tax return (he's too young and has no dependents)
*Even if somebody claims him, on their return, he still has to file his own tax return for his job income (assuming he makes more than $6350 for the year). He just doesn't claim his own exemption ($4050 deduction). At worst, he will receive $400 less if somebody else claims him. But that somebody else will get thousands (most likely)
