Sure she can. My mother did it with the three of us all the time. And on the single occasion I can recall that hushing my brother did not work, all of us left, with Mom apologizing profusely to all in her path.
As long as the parent is actively taking steps to solve the problem, most people are quite tolerant. It’s when the parent is letting the child wail, holler, whine, or otherwise carry on, and is clearly ignoring those bad behaviors, that people like me get snarky and are inspired to post about them on Websites.
You’re not a parent, are you?
One of my favorite restaurants is a place where the owner kicks people out if a kid starts misbehaving and the parents fail to remove the child and allow it to continue. He’s been known to get a round of applause from the other diners when he does this, too.
You know this happened on an elevator, right? Where should Mom have taken the kids, up the emergency hatch?