All of these people from out of state answer you, but they don't know the Texas law.
YES....the option fee is non-refundable. Typically this might be $100-$200.
You might try to get it lower since this is a backup contract.
I normally don't like to do back up contracts due to this reason and also that you tie up your earnest money on a house hopefully that has a good buyer and seller.
I normally just tell the seller that we like the house, come back to us if something happens. In the mean time you keep looking for the house you will contract on. If you don't find another and this one comes back then be in line.
It happened this week for one of my buyers.
Good luck...you'll find the right place.