You have a few options. Many people will strongly feel you must isolate her. There are different ways to do that, lot's of possible different details. The basics are to either build a pen to lock her in until she hatches or build a pen around her nest so she cannot get out and no other hen can get in. To either she will need feed and water.
I would not do that since they are under a nest, that's probably a pretty decent nesting place. I'd mark the eggs, I use a black sharpie and draw a circle the long way and another circle the short way so I can tell at a glance which egg belongs. After the others have finished laying for the day I'd check under her and remove any unmarked eggs. As long as you check every day you can still use those eggs.
There are some benefits, risks, and disadvantages of any of these methods. I don't know your set-up, management techniques, experience, goals or anything else sol I'm shooting a bit in the dark, but if you want her to hatch those eggs building a pen around her current nest is probably the safest way to go.