Clayton Markus is produced at Rowe's factory, and quality is really no better than a Rowe sofa, so I suggest taking CM off your list.
If your mother likes the sofa and chairs, then all you need to do is find a reputable upholster in your area. The re-upholster should have fabric samples to choose from and also can determine the condition of the fame and springs. Or you can buy your fabrics at a local fabric shop or online and most upholsters will work with your fabric. Depending on the area you live in, this would most likely give the results your mother would most appreciate.

Here is a link that might be useful: New custom sofas designed for re-upholstery

Thank you for your reply. Do you think there are not any decent brands now that will hold up in the long run and to go with upholstery instead?

Good quality high end upholstery is still being built by several manufacturers. Look for solid hardwood frames no less that 1" thick, that are double-dowelled and glued.
Hancock & Moore or TRS Upholstery is suggested.

Avoid the engineered plywood frames so many other high-end manufacturers are using now.

Tufted backs and arms with wood trims seem to be back in now!

For sofas, consider Precedent. Reupholstering will be the most expensive option, usually.

But, I'm not sure what you find "reasonable" cost. High quality furniture is really the better bargain, in my opinion. We bought a Century sofa and Henredon chairs 20 years ago, raised two children, and they were still in perfect shape when we finally sold them earlier this year (it was time to change our decor). Go into one of the better furniture stores/design studios and get ideas on what to look for. You may actually find a bargain that approaches the cost of the lower quality sofas.

FYI, Precedent, Century and Henredon sofas are built from plywood frames. Quality of these once high end manufacturers are not what they use to be.
So to find a comparable quality and style your mother currently has will be a challenge. So its worth repairing the springs and having it reupholstered, IMHO.

I appreciate all of your above input! I have been reading good reviews about Hancock and Moore. I have looked at a few of their sofas in another city, as they do not carry the brand in our area. The price they had was a Labor Day sale price of the low $2000.00's on one of their leather sofa styles, which ironically was a similar price at Haverty's for a fabric sofa. It is a price they can afford. My mother prefers fabric over leather. i have never heard of TRS, but will investigate. It is such a shame that the furniture industry has taken such a downward turn in the quality of their products!

SDW, if you haven't purchased yet consider Smith Brother's of Berne. It is made in the USA and have very high manufacturing standards. I am buying SB chairs and a Hancock and Moore sofa.

I second holly-kay's recommendation for Smith Bros. I have two love seats by them and after more than 5 years of heavy use everyday, they look exactly like the day they were delivered. There is no sagging anywhere and are absolutely perfect.