Melissa,
I can offer this being the age your parents are probably, we are 62 Gene 67. Our children age 40 and 36, were very helpful and watched over us when Gene was diagnosed. At times they hovered a bit much but I knew its only beacuse they are concerned.
I and Gene both broke down many times turning the months before his r/c.as the matriarchs we fel helpless as we are in that senior phase of life and is SCARY for us..we didn't know for 2 months how bad this was going to be.
I would go into a prevent mode, stick close by, tell mom your right there with here, and do what it takes to get them on a positive note. The cancer is scary enough, depression can jump in and make it more scary. Handling the unknown is the biggest concern. Our children visited just about everyday,, did the lawn for us, and brought the children to make us smile.
I hope it gets better for them both,
ginger