The next time she does this, buy mala hotpot every night and make sure she eats with you till she learns how to listen. If she don’t, I’ll say haiz you don’t like me is it. If she mentioned it’s bad, ask her back will it be so serious that it will affect her sleep and health if she eats mala at night.
Same thing for the 5:30pm snack, buy her food and make her eat before dinner time and make sure she eats normal portions during dinner time as well.
Above has to be done by your hub if you don’t intend to offend ur mil 😅 But I always tell my mil off if she don’t listen despite me telling her no. (After I have my kid I couldn’t be bothered about her feelings over my child’s health and safety tbh. Before I got pregnant, everytime she do nonsense stuffs I’ll just keep quiet.)