Stage 4 Signet Ring cell adenocarcinoma

Hi good night, I know this is a late post but I am petrified for my mom. She has been diagnosed with stage 4 signet ring cell adenocarcinoma since April of this year. She was completely healthy until she complained about pain in her stomach and not being able to eat much.
Is there anyone with this prognosis out there?
I am shattered to pieces, never in my life I expected this to happen to my mom. She eats well, she doesn't drink, she doesn't smoke, she doesn't party but yet met with this prognosis.
She is barely able to see since recently. It's like her vision one day was extremely blur.
HELP😭