imhotep, the only things that (apart from meat and protein based stuff) I have learned NOT to put into the compost bin are a) egg-shells and b) pasta. Egg-shells don't break down - some of my lovely 2-year-old compost is still full of egg-shells,! - and the layer of skiiny stuff inside the egg-shell is protein-based - and it's the protein which attracts the vermin. Likewise pasta has egg, milk, sometimes sauce, and will attract unwelcome attention.
These days I have a compost bin with contents roughly as follows:
vegetable peelings and waste
fruit peelings, cores etc
soft garden waste (not twigs)
egg boxes
occasional newspaper scrunched up
toilet roll insides
I have two bins so one year I fill up, then seal it for twelve months - so the worms and bugs can get to work! while I fill up the second one. Year two, vice versa. It works well, I have lovely compost at the end of it. Good luck to your mum, she's doing her bit!