Where exactly in zone 6? Sun or shade? Is water available to the area?

E TN. Sun. No water except rain.

Thymes and or groundcover sedums will do it--S. 'John Creech' is my favorite, but you can use others as well. Groundcover thymes (not available by seed, but a good selection from High Country Gardens.)

The groundcover has to be vigorous enough to suppress the weeds. Thymes and Sedums are too short and slow growing to do the job unless the area is very small.

A thick mulch of woodchips, applied after the ground is wet, would be a nice start. I use hardy Geraniums planted in woodchips.

Mike

English Ivy is one that would definitely work. Evergreen, water wise, very vigorous and hardy. If your friend isn't a gardener and just wants that spot covered, basically permanently, this would work. It's pretty affordable in blundles that are shipped as bare root plants, but they take fast and spread. 100 plants will cover 275 square feet right away. You can let them spread from there, or move rooted cuttings as they grow to where ever you want.

Non gardeners are less likely to limit the spread of ivy into the neighbor's yards is a reason it shouldn't be recommended in my opinion.

Mike

I understand that. I offered the recommendation based on the apparent needs expressed here. How the friend uses the advice here is up to them. However, English Ivy is easily contained by manual pulling, or using an herbicide specifically for english ivy containingriclopyr ester. Mowing
over it every spring where you don't want it to grow, then applying the
herbicide on the shoots that are left after mowing, will keep it
contained. It's a quick job.

And ivy will climb and smother all the trees and shrubs the gardener has just planted there. If weed suppressing is main concern, the gardener should try Geraniums 'Biokovo' or 'Karmina', both highly weed suppressing, fill in quite well, never invasive, semi-evergreen in my zone at least, and highly deer resistant.

Ivy can be a nightmare for everyone involved unless controlled and that would be hard to do on this hillside. I have decided to recommend Rockspray Cotoneasters to fill in. In my own experience I have found if the ground is shaded whether it be by groundcover or dense shrubs, weeds for the most part do not thrive. If it were me I would put lots of daylilys, rudbeckia, spiderwort, gooseneck and cover with lots of color. But alas, I am an avid gardener and she is not. Everyone wants an easy quick fix and as in life it doesn't work that way. Thank you to all for your suggestions. I was hoping someone had a suggestion I had not thought of but it is a difficult space.

Until your friend finds the right plant, sow crimson clover it

should keep some of the weeds down.