.. It could be something you don't even know about, and you getting it would have an emotional impact on your mother.
Perfect chance for me to slide an apt, drunken rant in. What Jaszek just said is 100% solid. When i started spending nights with my new GF at the age of 15, my mother didn't like it. The 'curfew' was an obvious punishment. It's not like i didn't see it coming, but was i going to ditch my first 'adult' relationship?
So i moved out. It was an emotional day. It hit me all at once what my mother had gone through to raise me to that age. I felt like crap for abandoning ship, but i was going to do what i wanted regardless. The last thing i did before hauling my bags out of the house was write a letter for my mum to find. It was covered in my tears, but told her how grateful i was for all the sacrifices she had made to raise me.
She was good about it. We spoke regularly. It made me realise how tough things had been for her. I signed up to job agencies and went to work to help pay the rent. It sucked, and inevitably it went to pieces. Instead of sitting my GCSE exams i was loading Lorries in a warehouse, pretending i was 18 so that i could get paid.
Needless to say my Mother saw it coming. When i wanted to move back home i had to ask if it was ok. Of course she wasn't going to say no.. but you have to ask...!
Long story short..do what your Mother tells you. It might seem like it sucks... but there's nothing more important in life than respecting your 'rents! I know that my mother still has the letter that i wrote her. In her eyes it's probably the only thing that's justified putting up with having with me in the first place; let alone raising me for 15 years!
You'll get your License eventually, and be glad when you do.. but your Mother is always right...even when she is wrong. Give her a kiss and tell her you understand. It's the least you can do...