Canceling/disabling the auto-renewal does not make the subscription stop.
The subscription will last for the time you have selected when getting it. (e.g. 1, 2 or 3 years)
Using avast or having it installed or not has no influence on the subscription.
It is like with magazines, you will have to pay for the subscription and it doesn't matter if you read the magazine or not.
As David said, if you have asked for a refund using the ticket system within 30 days after the subscription started avast will (and I have no doubt about it) give you the refund.
It doesn't matter what the reason for asking is, although telling avast (giving feedback) is ofcourse welcome and appreciated.
p.s.
Sorry to hear about your mother in law, I hope see had a good life and that everyone has nice memories about her.