Hi, Erin. I agree that Becky has given you good advice. Your mom is in depression and overwhelmed. It will take effort to get her out of it because she can't do it alone. My wife was very depressed for the first 9 or 10 months of her diagnosis and treatment. She was depressed at having lung cancer, she was depressed at having to go through chemo and radiation and all the side effects she had to put up with, she was depressed that she couldn't go and do like she always has.
Every patient of life-threatening diesease needs an advocate -- someone to do for them what they can't do for themselves. This means encouraging them to eat and drink properly (by the way, we discovered that every two hours to eat is not only better -- more chance of eating enough -- but it also keeps something in the stomach and helps minimize nausea), encouraging them to take their meds, encouraging them to get interested in something (besides watching TV all day) that will take their mids off the disease and give them something constructive to do. The advocate also runs interference for them in doctor visits, tests, etc., so they don't have to put up with the system until they feel like it.
Hang in there. Hang onto the hope. Tell your mom that my wife is Stage IV, was given 9 months and she is now 27 months out and expecting many more. Blessings to you and Mom. Don