Stay calm and let mama do her job. If she abandons the unhatched eggs, you would have to put them in a incubator. Put out water in a shallow container with some clean pebbles or marbles - to prevent baby chicks from drowning. Have chick feed available - momma will show them where & now to eat & drink.
Broody hens don't do things by half, do they? She replaced your lost birds (sorry to hear about that!) with some spare! Congrats on the hatch and as DD suggested above, relax and enjoy them. A good broody mom will need nothing from you but feed (starter for the little ones, mom can eat it too), water in a shallow dish to recent drownings and shelter for her and the little ones. If you're interested, here is a wonderful long thread on broody hen hatches with lots of great info: