Sounds like your mom has an anxiety disorder too. My mom had anxiety, and I never knew how to develop an emotional world without anxiety. I'm betting she doesn't even see how her own disorder is exacerbating yours. *hugs*
I haven't heard anything about an increased risk with the grid. The grid is a popular topic for doomsayers who just make up imaginary looming disasters. If your mom is anxious, ocd, or delusional about disasters, she WILL keep finding weird little groups that are convinced there will be a catastrophe each month. There are tiktok channels that will insist there's about to be a grid outage, natural disaster, nuclear war, the second coming of Christ, societal collapse, alien takeover, end of the Mayan calendar, etc. Every generation thinks it's living in the end times. Yet for centuries, predictions that the apocalypse will happen ANY MOMENT NOW don't pan out. Yet disaster dates keep arriving and passing, and people keep moving their focus to the next doomsayer. I guarantee that you will find a new looming catastrophe each month if you look for it, along with an echo chamber of users who are convinced it's real. And when the grid doesn't collapse in the next few weeks... I bet your mom will find some new disaster to worry about. Don't get trapped in her cycle.
That said, sometimes natural disasters and other disruptions DO cause brief outages. Hurricaines and snowstorms can knock things out for a couple days. Official advice is to always keep supplies to shelter in place without power for up to two weeks (or a minimum of 3 days.)
Rather than go down a whole research rabbithole, you can just look at https://ready.gov , which gives a realistic assessment of what kind of disasters are actually likely, and tells you how to make a practical preparation kit. Anything your mom does beyond these recommendations is just an overreaction to some doomsayer.
I hear you that your anxiety management relies on the internet. And 3-14 days without this support might feel unbearable. You might want to start practicing anxiety management techniques that can help you keep your head above water if you're ever cut off for a few days. Meditation, exercise, a hobby, etc. I know you've probably already tried these things, and found that online support is more effective. But what we're looking for here is to develop a skill that's good enough to get you through a few days without your better supports. You can also consider which online supports can be brought offline. Like a paper journal instead of journaling apps, recording your favorite youtube meditations to cassette (or just to your phone, which can stay charged with a solar panel to keep access to offline content), getting a deck of cards if you like to play Solitaire on your phone, etc. You probably have online support groups, and that's hard to replace. But you might find it helpful to bring this concern up to them now. Maybe write encouraging letters to each other to print out and read in each others' absence.
I also think you should consider that being afraid of losing your support for anxiety might be OCD. It sounds very OCD-shaped, "I have anxiety that I can't handle alone and I'm anxious about losing my supports because horrible things will happen if I can't manage my anxiety." What actually would happen if you were very anxious for a few days? You would feel terrible, which sucks to go through, but would it actually destroy anything?