My mom's van is not shifting right

This sounds very much like a fluid issue. When the vehicle is low on fluid it will not shift correctly, and the pump will make a whining noise as it is trying to pressurize air rather than the fluid.

So, we need to start with checking and changing the fluid to make sure it is not the issue.

Here are guides that will help with this:

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

If the fluid is not causing the issue, then we more than likely have an actual pump issue which means we need to check the pressure in the unit and that will determine what direction we need to go next.

Please see the attached test and let us know what you find. Thanks