It is a process, and one you seem to have well in hand, especially creating time alone with your mom, and a safe space in which she can unload and process her thoughts, concerns and issues, without feeling manipulated, pressured or threatened.
If and when the time is right, you may want to direct simple questions toward your mom's main blind spot, namely the whole gospel, especially according to Paul.
For example:
Mom, I have a few questions I would like to ask you about the "good news" in the Watchtower library (on computer or on the internet). Please can you let me know if and when you are able to set a day or two aside for this?
Are you a "publisher of the good news"?
How long have you been a "publisher of the good news"?
Is it true that the (Watchtower) Bible refers to "good news" around 152 times?
Is it true that more than half these are by Paul?
So what is the "good news" according to Paul?
How many times does Paul mention "good news"? (85 times)
How many times does Paul mention "good news" and "Kingdom" in the same sentence? (zero times)
Why?
Copy & paste whole link: http://wol.jw.org/en/wol/s/r1/lp-e?q=%22good+news%22&fc[]=bi