Anonymous wrote:She's a Fundamentalist Hindu Radical? How so?
They definitely exist.
OP - I would just make sure your children know what is actually behind the vegetarian teachings in Hinduism. I'd pull out some quotes from the Gita and tell the children it's important to go to the original source of holy teachings, not just listen to what anyone and everyone tells you about it.
When your MIL declines an invitation because you've had meat recently, just say "Sorry you can't make it" and end the conversation. She's free to do what she feels she needs to and you're free to cook how you please in your kitchen. When she's ready, she'll come over and either she'll eat with you or she won't.