I’m so sorry for your losses.

It’s probably best to get companions for your remaining bird as soon as possible. Chickens need a flock, and being surrounded by companions may help your remaining bird to de-stress.
However, I would suggest getting birds that are at least a month or two old, or getting chicks and waiting to introduce them until then. They should be big enough to run away from or stand up to the older bird.
Also, getting at least three or four new birds will help the introduction be more equal.
In the meantime, spending time with your remaining bird will help her not be lonely, and allow you to monitor her for signs of shock.