Does your mother take other medications? Some common medications deplete nutrients.

When was that B12 test done? I would like to see the numbers before giving you doses for the B12.

Is your mother getting up to urinate? Because of pain, or some other discomfort?

My doctor's rule is one night time visit to the bathroom is normal in older patients. More frequent visits indicate, hypertension or cardiac or diabetic problems developing.

I find that now that I am older, I tend to go to bed EARLIER than I used to. In fact I used to work nights most frequently. So if I go to bed before 9pm, I do get up at 1-2 am to visit the bathroom. Some days, I get back to sleep and other nights not.
You'll see me online during the "not" times!

I'd start CoQ-10 now. If you get the new aqueous form 100mg a day should be enough. If you buy one of the older, oil based soft gel cap, higher doses are needed because those are less absorbed. Say 300mg a day. I gave you a link to one brand. You can Google "water soluble CoQ-10" and find others. CoQ-10 strengthens the heart muscle and reduces heart failure, and blood pressure, and can help with night time bathroom visits.

All the time your mother took the statins, they blocked her liver's enzymes that synthesize CoQ-10 in the body. So all the systems would have been impacted, and perhaps damaged, over time. I'd start the CoQ-10 first, using a good product and see if her energy returns. It will take a while though.

B12 if low, will result in insomnia. She can try 3mg of Melatonin at night to see if that works. If it does, it points to low methylcobalamin in the brain, which is the cofactor in converting serotonin to melatonin.
This is blocked by some drugs too, Prozac and beta blockers mostly.