There very well could be something stuck in her airways causing this honking noise. I'm not sure what you could do to dislodge it if there is something in there. You might injure her trying to remove it. I don't recommend meds for this, it will have to be coughed out or work it's way out on it's own.
I had a hen that lived to 14 years of age, at age 6 she started honking occasionally, as the years went on the honking became more common. I could only assume her airways were collapsing just from age. She honked quite a bit at the end, daily, hourly, it never caused her any breathing or health issues, I never did figure out why she honked.