If the fire was truly an accident, you don't have the biggest component of insurance fraud. Creating a loss for financial gain.
She paid the premium and the contract was in place. If you rented a property on the up and up, you would get nothing from the property owners insurance post fire. The land lord policy will even pay the rent that's lost because you can't charge rent on a property that's uninhabitable.
You needed a renters insurance policy to pay for your personal property and additional living expenses.
Do you have any ownership interest in the property? It's not clear in your post if you're renting from mom or you believe this is getting you an ownership interest in the property.
At the end of the day, tenants without renters insurance are up shit creek if there's a fire.