What is the best small business for retires, that has flexibility?

• Begin a Blogging Business
Blogging is one of the most flexible and fun ways to make a living from home. You can write on your blog any time of day or night. You can work for hours at a time or even ten minutes throughout the day. You can select any topic that tickles your fancy and talk about it. Do you love movies? Create a movie blog. Do you know a lot about growing a garden on a terrace in a big city? Begin a container gardening blog. Are you fascinated by European history? Begin writing about it and ask people’s thoughts on the historical facts. The key to success in blogging is picking a topic that readers like to know about. This is done by posting new and exciting content regularly and getting the word out so people can find and see your blog. There are many ways to make money from your blog, like contextual ads, affiliate promotions, selling ad space, or making your own digital products like eBooks.
• Start an eBay Business. 
There are millions of things for sale on eBay at any given time. You can register yours early in the morning, late at night, or any other time. As soon as your item sells, you pack it, stamp it with postage, and mail it. The key is to sell products that people like, a good image, and an enticing headline and description. To begin with, get rid of items you don’t want or need around your house. If you see something selling well, look for a ready stock of that item at yard sales, thrift stores, or wholesalers online. For example, used golf clubs are a profitable but niche market, as are children’s games. 
• Work at home as a writer.
Writing is a quick, easy, and low-cost way to build a home-based or freelance business. Writing contains many jobs, including freelance article writing, content marketing, blogging, and more. You can sell your work yourself through a website or, in the case of eBooks, through Amazon Kindle, Nookpress, and other eBook distributors. Or you can write for others. While breaking into this job can be time-consuming—and you may experience many scams on your way—freelance writing is a growing field. You can find customers through your own website or networking on social media like LinkedIn.
• Start a transcription business.
Transcription is an ideal virtual support job if you can type fast and accurately. Most customers will have a due date by which they need the work, but the time of the day you do the work doesn’t matter as long as you deliver it on time. Many businesses require transcribers, including speakers, online entrepreneurs who do webinars, and associations.