dog biting with growling

[Sammi028]

My dog is almost 2 and since I moved a year ago and I wasn't able to bring him with me because my apartment doesn't allow dogs he has been getting really aggressive and biting my mom, but he doesn't have any behavior problems when I go to visit. Does anybody know how I can get him to stop biting my mom, he only bites her when he knows he has done something wrong and he's in trouble. We are at out wits end and don't know what to do and don't want to have to put him down because he bites someone really hard and breaks skin. We have tried a muzzle, but he behaves only until the muzzle is taken off. He usually bites her after he has peed in her room and knows she found out, so I know it's because he know's he's in trouble. He is a Silky Terrier and I read that they can be aggressive, but he is always barking and peeing on everything so as you can read from that, he has gotten in trouble a lot. Any advice on any of the problems would be much appreciated.