There are many ways to find Open Source project to contribute to, one of them is through the Open Source Software foundations.
Wikipedia has a page listing all (?) the organizations. Some are location specific (in a specific country), some are project specific, others are „umbrella organizations“ supporting a number of projects.
One could go to this page, find a cause that is close to her heart and look around which organization might support that cause. Then she could go to the projects supported by that organization and all the dependencies to see how can the cause pushed ahead.
Have you tried this route? How did it work for you?