Hi. I live with a live-in landlord currently, and I pay £80 a week / £320 a month. This covers all bills (including wifi & TV), and I'm allowed to use basics like milk, bread, butter, sugar, salt, etc. I still buy all my own food though, and pay for my own travel. My loan is just over £5k for the whole year.
I don't know what's going on with your mum's finances. Did you pay board before? If not, why does she suddenly need the money coming in from you? I definitely think you should buy all your own food and such, it'd be cheaper for you and it'd be yours alone. Try and work out something, maybe you can have one shelf in the fridge, a drawer in the freezer and some cupboard space for your food which only you eat. If you look at your bills, work out what's fair for you to pay. If you think your mum's being unfair then maybe move out. At least with other landlords / accommodation, everything is official and they can't just ask for more money or change the rent randomly. I would say that if the money's disappearing from your mum's bank account, she can call the bank and ask where it went out to (prepayments, to cover an overdraft, direct debits, etc). They will always be able to find out why the money left the account and if they cannot, then there is definitely something wrong and they'd probably investigate it. All incoming and outgoing money from an account is tracked. If she wasn't putting it in the bank before, absolutely make sure she is now.
I don't know how much your loan is, or what the cost of living in your area is. But I'd say you're living pretty cheap by staying at home. Depending on what city and area you're in, student accommodation can be quite high. (I actually can't afford to live at any of my uni's student housing since they're all over £5k, more than my loan in full).
£60 seems like a lot for living at home, since it's your parents. But you're probably going to be most comfortable there if this situation doesn't happen again. If you know it's going to keep happening, then it might be best to move out. But you could always lodge with another family member (grandparents, aunt/uncle etc) or at a friend's house and pay board.
PS: If you need to earn some extra money, like £10 / £25 every other week or something to help with payments, you can try sites like Vivatic and do surveys for money, or get paid for downloading and testing apps on your phone with Featurepoints.com and use code 2ZYHEC to get 50 starting points.