No, you will not need to pay any capital gains. When calculating capital gains/losses you take the original cost basis ($60k) and subtract it from the sales price ($53) so in this case there would be a $7k loss. Normally since you did not use the house as your primary residence you would be able to use that capital loss to offset other income.
However, in this case since you never contributed any of the initial cash nor received any of the proceeds, 100% of the loss would be used on your mother's return. If you try to claim a portion of the loss you would run into the gift tax rules so I recommend you do not claim that loss.
You will receive a tax document showing the sale for $26500. What you need to do on a Schedule D is to show a sale of $26500 and a purchase price of $26500. This will have no effect on your tax return. What is will do however is keep IRS from coming to determine why you did not report the $26500 and having to go through the explain of what transpired.
This should be good news to you - you will owe no taxes. If you still have a specific question please hit the need info button and ask. If you are satisfied with the answer please hit the green accept button to close out the question and allow me to receive payment.