I am sorry your hen lost her eggs so sad when so close to hatching.
I have to keep my coops closed up during the day now. In the past I have had them eat developing eggs and it is heartbreaking for the hen and for me, so this year I tried a different approach i leave a duck egg on the floor but what heppened here was then it was hiding out in the coop instead of leaving [I mean I was offering fast food why go away] I caught it and here they get to 6' long and carried it off. I don't think it matters they know where free food is. So I set up in a small coop and some dog houses we have for the birds to get out of the weather with shavings so they can lay their eggs out of the 2 main coops since they are closed once everyone comes out in the morning. I have one coop with a mama and 2 ducklings no way I want a snake in there the other coop has a broody goose[no eggs] and 2 broody bantams [no eggs]
Oh and yesterday my broody Orpington was in the small coop and I heard all this commotion and thought oh great one of the big hens is picking on her well she was attacking a big black snake I mean attacking it even pecking at its head. that snake
did not even try to defend itself it was getting the heck out of there lol.
A few years ago I had a 6' one hiding in the coop and it came out at night and tried to eat a 4 weekd old bantam cochin and of course all it did was suffocate it.