how long can you stay after the visa expires?

[vidya]

My friend's mom has a multiple entry visa and her I-94 is valid for 6 months. Is there any grace period for the number of days she can stay after this exp date. In Canada they give a grace peiod of 90 days.
Also, she has applied for I-130 along with I-485. Would that make any difference for her to stay after her I-94 exp.
TIA
vidya

[immihelp]

person can stay only up to I-94 expires.

There is no grace period.

Having filed I-130 does not make any difference.