Protecting a broody while she's incubating her eggs and later, protecting the chicks after they're newly hatched is a practical problem best addressed as a long term solution.
Several years ago, I built a second coop. I cut three doors into it, two leading out to the main run and the third one opening out into smaller run. I also divided this coop down the middle because at the time I had two roosters in residence that wanted to kill each other.
Those roosters are now gone, so the side of the coop opening into the smaller run is now the broody coop and run. I built a roomy nest on the floor for the broody, and when my broody was ramping up her hormones, I began "suggesting" she use the nest by taking her out of the regular nest she was planning on laying her egg in and placing her in the broody nest in the special broody coop.
It didn't take long and she was happy to lay eggs there, and when she went broody all the way, she was ready to plant herself there for the duration.
In the past I've also moved the eggs from a main nest and placed her on the eggs and locked her in. She would complain for a bit, but the lure of a nest full of eggs, assisted by her crazy broody hormones, eventually overcame her stubbornness and she remained.
So, I recommend you look at this beyond this immediate broody. How would you ideally like to be able to manage your broody hens and chicks? Just do it!