On Mother’s Day last year, Michelle Wilcox was planning her funeral. This year, she and her husband will fly from Chicago to Dallas to meet a granddaughter she was told she might never see. The mother of four is alive more than a year after being diagnosed with leptomeningeal disease, a rare and aggressive cancer that spreads to the lining of the brain and spinal cord and is often fatal within weeks. “When someone tells you you have a month to l…