Humans have no rhyme or reason whatsoever. Just give them one of those long intense haughty stares, it always unnerves them.
I'm not sure why they won't let you play with that wonderful new toy, it even smells so nice, doesn't it? And it's so extra tall, with really cool toys dangling from it, some even make a really good crash on the floor and split into more toy pieces. We aren't as lucky as you, we don't have one of those toys, I heard Mommy saying that we would rip something to shreds in 2 minutes. I heard her call it a "christmas tree".
It's not just your Mommy that doesn't know how to eat proper food. They're mostly kinda slow-witted, and don't get a lot of things. Don't give up, keep bringing her the good mice, and eventually she'll figure it out. She can't stay hungry forever.