I've never had a bird taken by a predator without leaving evidence, usually lots of feathers. (Some people disagree with this, but I've been told that the only predator that can carry off a bird without leaving obvious evidence is a human. If you don't find her or any evidence of a struggle, ask your neighbors if anyone was around today.) I've had birds (chickens) not be in the right place 8-10 times at bed time. Usually they were either on a nest or roosting in a tree. Once a hen was trapped under a tarp that my husband had put over a tractor (found her the next afternoon because I just didn't believe she could vanish without a trace, and started looking everywhere, even the places that I knew she couldn't be). Once a hen was trapped in a locked room in the barn, found the next morning. Once a bird jumped in a friend's camper shell, but was found before he got too far down the road. A few times I never found the bird despite extensive searching, but she was waiting by the food bowl in the morning -- never figured out what happened. I've never had a broody leave for weeks and then show up later with a clutch of chicks, but I hear it happens all the time. (But that would seem unlikely in your situation, as this hen lays eggs in the barn.)
All you can do is keep looking. Get family and friends and lots of flashlights, and keep looking until you find her or evidence that a predator took her. If it's already dark she's not going to budge from her hiding spot when called, no matter how tempting the food treat rattled in her bowl. When looking up in trees, sometime looking with a flashlight is best, and sometimes without a flashlight is best. Different eyes see things differently, especially in the dark, so have multiple people look over the same areas. My husband has very poor night vision but sees birds hidden at night with a flashlight better than I do. I have excellent night vision, but using a flashlight in a tree makes me focus on the near branches, so I see shapes in the center of a tree best without a light. However you use your flashlight, be sure that the batteries are new to get your best visibility.
If you or a friend have a dog with a good nose, that's probably your best option, as long as the dog won't injure the bird.
Or, in the unlikely event you or a friend has a FLIR unit, you can use that to search for her. A FLIR unit is a thermal scanner that picks up hidden heat. Most people think of it as being used by military special forces or SWAT units to determine how many bad guys are hiding in a room behind closed doors, but lots of contractors, building inspectors, plumbers, realtors, energy use consultants, etc use a non-military version to evaluate heat loss in homes, leaky pipes, drafts, etc. If you know someone that has one you might be able to find her hiding when you can't see her.
Good luck on your search. I know you always think the worst, but as long as you don't find evidence that she's been killed, there's always hope.
Thank you! I had looked everywhere and I can't imagine her roosting anywhere other than her usual perch in the barn. Her nightly ritual is to jump on the lower perch and mess with the chickens for awhile and then she goes on her perch. There was someone here to drop off the lawn mower blades he sharpened for us. I know she was there prior to his arrival to the house and I didn't see him actually leave and my first thought was he took her. Me seeing her and her disappearing all happened within a matter of 2 hours. This disappearance is very unusual for her. My other 2 hens and the Tom were there in the barn tonight. I looked in and under everywhere with no sign of her or something happened to her.