You are saying this:
You are a client. You created a job posting for a fixed-price job.
A freelancer applied to your job and agreed to do the job.
You clicked the "Hire" button and funded an escrow payment.
But the freelancer has not yet accepted the offer.
How long has it been since you made the offer? An hour? A day? You may need to be patient. Maybe the freelancer did not have time to accept the contract offer yet.
You are welcome to message the freelancer to ask if she plans to accept the ofer, and when.
You are also welcome to rescind the offer. If you cancel the offer, you will receive all of your money back within 5 business days.
You are welcome to hire somebody else. You DO not need to wait for this other freelancer.
It is your project, and your schedule.
You may hire as many people as you want to do this task.