Hi, Cristiane, welcome to NeuroTalk!
That situation has to be so difficult for you, I'm so sorry to learn about your mother having ALS. Ugh, it's such a difficult path.
I don't know what kind of communication technology is available in your homeland but wonder whether they have TTY, which is a teletype telephone system that uses a small printer similar to that of an adding machine. The deaf use it to communicate by phone.
If your mom is able to write, perhaps she could use a TTY to talk to you in her own power. You would be able to read her messages in real time while on the line with her.
Here is a link to the ALS forum where some of the good people might have ideas for you:
http://neurotalk.psychcentral.com/forumdisplay.php?f=6
I sure hope you can find a solution, I'm sure your voice does a world of good for your mom's spirit. You sound like a wonderful daughter!