What do I do about my lab/pointer mix?

I'm actually asking this for my mom. She has a 1 1/2 year old female lab/pointer mix that keeps on scratching the walls up...pulling up the carpet...chewing around doors (through drywall!)... and refuses to be crated. She's 85 lbs. and they just can't get her in what so ever. She is housebroken when they're home, but not when they're gone. She thinks the dog may have seperation anxiety, but not sure how to handle it. When my mom and her husband are home, she's a perfect dog. Her husband wants to get rid of the dog, but my mom say's "no way!". They both have full time jobs... what can they do to help the dog learn not to do these things anymore?