Animated kids movie, the characters are animals (Possibly Mice), the Protagonist is a young boy who's ill mother dies and he's left with his super rich evil step father....

Think animation style of Fievel Goes West, An American Tail, very Disney VHS movie style. I remember seeing on TV in the 90's. There's a chance the characters were foxes instead of Mice I really can't remember. It could've been a TV movie but very much felt like the above examples.

I just remember the story starts with a Mum and Son where she's super and poor. She agrees to Marry the wealthy rich guy but dies and the son is left with an evil step father who runs a big company.