what you can do to see if she enters your apartment illegally after you leave (and hopefully your mother doesn't go out) is place some clear tape over the door between the frame and the door. if the door opens the tape will be broken and you will know. don't use wide tape , that would be obvious and do it near the bottom. you can also place something by the door inside son that mom would have to move it to open the door..it's hit or miss if she does but you'll get an idea.

it's very low tech but it works. you will know if your door has been opened. trust me.

take a pix of the tape with a ttime/date stamp on your phone each date when you leave & return...this way you will have proof. hard to complain to corporate if you can't prove anything...