The same goes for the childless housewife, but I was specifically asked to write about empty-nesters.
"I got a letter from a woman whose children are grown and married and they have no interest in her, she feels really lost and she wanted suggestions"
This is a situation which, unfortunately, happens only too often, however, children don't even need to leave the house. As they grow older, they develop their own interests and friendships, and can basically take care of themselves, so that the mother feels somewhat lost, and the pressure often mounts to get a job.
That's why it's very important for a housewife to have some interests and hobbies outside of the realm of child-rearing and have her own friends who can drop by for a cup of tea.
There are lots of things an empty-nest housewife can do. First, let's not forget that most ladies who are in this situation fall into the category of older women, which means that they generally need more rest and housework is still there, plus there are no children available for help any more. When you get older, you need to invest more time and effort into preserving your health, which means taking long walks, exercising, and the like.
Remember, you still have your husband to take care of, and you surely would want to stay in good shape for him and for your children, when they need you. Your parents and other family members may require help, too.
Another ages-old way to occupy yourself is needlework and crafts. That's the traditional female work which even aristocratic ladies didn't count beneath themselves to perform. You have a choice between knitting, cross-stitching, quilting, making clothes, household projects etc etc, and some adventurous women even learn spinning and weaving. Neeedlework can give you hours of pleasurably spent time (it can be combined with watching movies/listening to audio books) and you will have some beautiful hand-made product in the end.
If you have a garden, now it's time to give it the attention it always needed. Gardening is another "genteel" occupation. You can also learn to draw or play a musical instrument or take classes in gourmet cooking. I once met an older lady who got interested in Ancient Rome, learned Roman cooking and became a historical reenactor. You can learn a foreign language or study calculus. There are lots of things to do, if only you realise that first, life didn't end because your children left the house and you are older now, and second, you can be a childless housewife and still find enough to do.
"Women like that are vulnerable to home business or careers or ministries"
I think I covered the subject of careers well enough, now a couple of words about home businesses. I think they are OK, if they bring money instead of costing money, and if they don't distract women from running the household, which often happens. I keep reading stories of men who complain that their wives lose money on their home businesses and the house is never clean, or that their wives babysit for less than minimum wage when the husband makes a decent living.
The same is true about ministries. Your first ministry is your home and your husband, it's fine to help in the church, to sing in a choir or to teach Sunday school but when the ministry starts resembling a full time job, you are probably taking it too far.
There is a wonderful blog, called Mias Landliv which I mentioned several times before, where the lady owner shows her garden and her beautiful handworks. It can give you a couple of ideas. I also suggest watching old TV series like I Love Lucy where Ethel was a childless housewife (Lucy was also one till the middle of Season 2), or I Dream Of Jeannie where Mrs Bellows kept an ideal house and practised hospitality.
Well, I hope this was helpful!