She's likely still suffering trauma from the attack. I had a young pullet a couple years ago survive a hawk attack and lost every single feather on her back, yet not a single scratch. This particular hen is a loaded pistol. She launched herself across the yard and into the coop, not breaking momentum, during and following the attack, and she never suffered from it in the least. She's still a force to be reckoned with. Other more timid chickens can suffer post stress after such an attack for weeks, even though they weren't harmed otherwise.
The only danger I see is that your Silkie is of a timid temperament and prone to remaining in stress for an extended period. In other words, for timid chickens, if a condition lasts too long, it can become habit. You need to interrupt her withdrawal somehow.
You will need to try different things to see how you can change her view of her world as too dangerous to eat. Sometimes, reducing a timid chicken's environment to a small, very secure place can help get the process started.
To feel secure, a chicken needs cover, literally. A crate with a solid top placed in a quiet spot of the coop or run is one idea. Start the Silkie off with some favorite food such as soft boiled egg or yogurt and don't forget to provide grit. Then slowly try other foods until you get her interested in eating again. Try to keep her in the flock so she still has the comfort and security of their company.
Depending on how it goes, she may be ready to go back to her normal way of life again in a few days of TLC.
