Help Mom Fix Grandma's Flooded Bathroom

Hello! I'm making this for my mother. She would never ever do this for herself. She is the most selfless person. She truly puts everyone's needs long before her own.

My mother is currently taking care of her mother, my grandmother, who earlier this year suffered a suspected stroke and on Easter suffered a widow maker heart attack. You could say the punches just keep coming! My grandmother has her own little apartment in the downstairs portion of my mother's house. It's become apparent that there is a major problem with the plumbing pipes. Every time the shower upstairs is used or the toilet is being flushed, it's flooding my grandmother's bathroom.

My grandmother needs a safe bathroom to use. They had a plumber come out this week and they have quoted my mom $8,000-$10,000. ANY help would be soooo beyond appreciated.