Newly qualified driver here, so I can very much relate to your situation!
I learnt in a manual because my parents were keen that I get a full license and could consequently drive any vehicle. I didn't much like driving on a manual transmission, so my current car (first car) is automatic, and I'd never go back. It's so convenient. That being said, learning in a manual forced me to think much more about my actions and made me a better driver. With an automatic, there is always the risk of mindless driving, so you must be vigilant. Of course, this is all subjective and your driving will very much depend on individual skill.
However, I think in this day and age, with many manufacturers switching to automatic output/electric (look at Fiat's recent move to all-electric Fiat 500's), the idea that you'd be driving a manual car in some sort of hypothetical scenario is ridiculous - it almost never happens. Short of going on holiday to a country where automatic transmission isn't popular, I can't see any reason why you'd be driving anyone else's car.
I'd take your mother's advice, especially if she's supportive - you'll learn so much quicker in an automatic and they're a pleasure to drive, even with the slightly increased price tag.