If it says that service may be discontinued, I doubt it's a matter of just forgetting. Usually you get a number of warnings for an "essential" service before they'll cut it off, and they have a lot of specific guidelines about cutting people off (for electric, gas, and water, because electricity or gas may provide essential heat in winter, and water is, well, kinda essential to life). So if it says they're being cut off, my guess is they're probably pretty far behind.
I think she could certainly call the electric company and ask if she could pay the bill, but they may not be able or willing to give her the information. They might be willing to apply money to the account as an anonymous donation without telling her how much is owed, but depending on how generous she is able or willing to be, this may or may not help them. However, even if it ends up being less than the total that is owed, it might "reset the clock" on how long they have to pay the bill, since some part of the bill was paid, so it could help them in that sense. I guess it couldn't hurt to call the electric company and see what she could do. The worst they could do would be to say no, right? I doubt the company would call the couple to report the snoop.