Could this not be read as "Don't give him (the) food"?
Yep, that should also be fine.
Why can't it be her or him. Eg Do not give her/him food. explain
You're using 'us' as opposed to 'uske', that seems to refer more to objects based on other questions (from my understanding).
उसे खाना मत दो should be translated as Do not give food to him/her
This feels like a scary movie reference
Do not give it food
Would "उस खाना मत दो" translate as "Do not give that food"?