You can also use non adhesive shelf liner.
Tell your mom that there are health risks involved with calcium sand. As the above poster said, it harbors bacteria more than using the tiled surfaces, plus, it can cause impaction. Some beardies will ingest the sand and if it builds up in the animals stomach or intestines, it can kill the reptile. Have her look at this thread here:
viewtopic.php?f=34&t=132151
Not only that, try and use the argument of cost. You will need to add to or clean out the tank periodically and refill the sand. This is an expense that can be cut by just using tile that lasts forever (unless you drop and break it) or the shelf liner.