For a start, she might try speaking with the folks at the Senior Center:
http://cstx.gov/index.aspx?page=626It is a place where folks get together and they have a variety of groups as you will see from the link.
If I think of some more I will edit them in.
Edit:
After some reflection, here are a few ideas for you...
Will she be attending a house of worship? There are a lot of great churches here and lots of friendly congregations.
Any particular interests? There are quite a few groups from politics to pickleball. Master gardeners, bird watching, card games, fantasy football, darts, running, cycling, triathlons, alumni groups from several universities, beer making, wine making, cooking, painting, travel groups and so on.
There are also a lot of volunteer organizations if her work hours permit.