I'll probably get a bashing for this, but speaking from experience, this is exactly why it can be difficult to be friends, as an atheist, agnostic, or a different belief system to a friend, with some people whom are very religious.
Sometimes, their individual interpretation of those beliefs delve into the extreme realm, and such individuals seem to lose their filter, in the strength of 'spreading the word'. Yes we can attribute this to just individuals who are nasty, but having some family whom are deeply religious, as well as (some past, some current) friends, it's genuinely my observation that this seems to be a common trend, moreover, the individuals saying such things genuinely believe them, however out of this world it seems to us.
I'm not religion bashing. I do genuinely have respect for others religions, feel I'm quite open to them, and enjoy learning about different religions and how they have influenced cultures. As an atheist, I have truly lost count of the number of times I've been told I'm going to hell by Christians & Catholics. Never experienced it with my conversations with Muslims, most I've conversed with are pretty respectful although just the other day I did meet a pushy one. Never experienced it with Buddhists either. And yes, I've met pushy, offensive atheists too. Although granted they seem to push their agenda via social media, yet to meet one who verbally pushes it, personally.
Your 'friend', has some very toxic aspects to her beliefs, regardless of what those actually subscribe to. She was out of order, on such a grand scale I'm shaking my head behind my computer. I'm so very sorry she said this to you at all, but even worse, when you have just freshly lost your dear mother and are no doubt in deep grief. It was a deeply emotionally & mentally harmful thing to say, but I'm afraid your friend is so lost in this shit she will never see it. I speak from experience here, just drop her. It won't get any better, and when someone reaches the extreme scale of beliefs seen here, in my opinion it will only get worse, if it even can for you, at the moment.
I think I saw mention of mental illness futher up thread. I do personally believe some of the cases of extremism we see (such as this), where those beliefs damage relationships with friends and family, are often mentally not 100%. Again, not something that can easily be solved.
My sincerest condolences to you on losing your dear mum. You need only surround yourself with positive people who are conductive to aiding you, where possible, through the grieving process. Be choosy, and be selfish about those around you. People such as this 'friend' can be severely damaging.