"She just started using the Green Salve from Hummingbird Lane at bedtime for back pain/arthritis in place of an evening dose of Tramadol. She told me she was feeling very tired and groggy this morning after having slept pretty well. 73.85 mg THC, 13/59 mg CBD and 1.37 CBN. Is this too strong to start?"
I would try a CBD:THC tincture with ratio of anywhere from 60:1 to 5:1. Start with a small dose, observe for a few hours and increase the dose slowly, giving three to six times per 24 hour period. Cannabis is non-toxic and well tolerated. She may also benefit from inhaled cannabis.
That would seem to be a pretty high dose of THC for someone whose tolerance is likely to be pretty low.
But if you drop the total dosage she will get less CBD and CBN– CBN seems to be the important one for sleep. However I do not know if CBN might contribute to grogginess the next day.
So maybe try Alta California Botanicals Insomnia Relief Tincture.