Hi Lisa:
welcome to this group. I think your dad has a pretty good chance at beating this disease from what I have seen in others who have had limited sclc. You say your dad is on medicaire for disability. Does he get an income from ssdi? That should help too. If he has both medicare and your mom's insurance, he should have double coverage. I think the rule would be that medicaire is his primary coverage and the private carrier is his secondary coverage. If your mom's insurance knew he was eligible for medicaire, I think they would insist that he go through medicaire first, and that once medicaire processes a claim, it can be sent to yur mom's insurance. Usually haiving double coverage does not help much until you start having a lot of medical expenses. Your dad might want to look in to using both coverages. I had double coverage last year. I think I paid about $500 total for very expensive surgery, chemo, doctor visits and numerous scans and xrays.
I hope your mom has a good meeting with her pcp. It might help her to go on an antidepressant such as lexapro for a while. Taking antidepresants is a common acitivity at this board for survivors and caregivers both.
Tell your dad that we are all rooting for him to stay focused, get through his treatment and to beat the cancer.
Don M