Selling My Ball Python? </3

[Bluebonnet Herp]

The thing that my mother is really concerned about is that she thinks my snake will grow too big and possibly escape its enclosure...

Funny thing- ball pythons became popular because they tended to avoid this problem. Provide the proper sized enclosure and environment and the ball python will not try to escape, and secure the enclosure; the ball python couldn't escape if it tried. Make sure the terrarium has clasps/clips/locks or whatever secures it, and make sure your snake's environment is up to date. A happy ball python just hides all day- it wouldn't bother moving around if it has water, the right temperatures, humidity, and a snuggly hide.
An adult ball python will need a 20 - 30 gallon breeder vivarium or equally sized tub/enclosure when it is an adult. Keep this in mind.