Effects of overstaying on visitor VISA

[phs]

My MIL is here in USA on visiotr visa ( which is valid for 10 years ). She got her I-94 stamped for just 2 months, instead of 6 months. We already have her return ticket in hand which is after 5 months. What will be effects of overstaying ?
I just wanted to confirm she won't have any problem while returning to India. She will not be coming back to USA, so I am not concerned about re-entry. Just wanted to make sure she won't have any issues ( police or any other legal ) at airport and returns safely to India.

[immihelp]

Overstaying means illegal.

People illegally in the U.S. always the risk of getting arrested, going to jail, fined, deported etc.

What exactly will happen to a particular person, no one can say.