Sounds to me like she is ready to rejoin the flock with her babies. I would put something down on the ground that is able to be secured at night for safety for her and the chicks to sleep in. In my experience, momma will try to convince the chicks to come up the ramp with her and then finally give up and stay down below with the chicks. Most of my chicks were able to figure the ramp out at about 1 week old, but she probably won't abandon them if they can't make it up the ramp.
This is what I would do. After providing a box, dog kennel or something else that can be used as a nest for the momma and babies, I would wait to go out until it is almost completely dark and see where everyone is. I know that that is a scary situation, what if you can't find them, etc. Sometimes, I'll take a chair out and sit a short distance away, but not interfere with the nighttime settling down. Wait and see what happens, but be there so that I can assist if it truly gets dark and nothing is resolved. My broody would frequently wander a short distance from the babies to get a dust bath, eat, even sometimes just to see what everyone else was doing. As soon as one of the babies was in any sort of distress (such as another hen approaching) she'd tear back to them all puffed up ready to do battle. Your hen must trust the frizzle or she wouldn't leave the chicks with her/him. Mine always slept under the coop (4 feet above ground) for the first week with her babies, then would move into the house once they could all get up the ramp (sometimes this could take close to an hour for everyone to figure it out) but slept in one of the nest boxes on the floor of the coop....not in or on roosts or higher nest boxes. Then she would leave them at about 4-6 weeks and they would have to figure out where to sleep until they felt they could join the rest of the flock on the roost (usually on the floor huddled together).
Hope this helps to settle your worries.