What could be one of the reasons why Ma gets so annoyed at Jack talking about Lucky? Maybe because it reminds her of how she was kidnapped.
Other than the times when she's Gone, Ma is completely, 100% selflessly devoted to Jack and has given up what little semblance of independence she has in captivity to devote herself to his well-being. Her single act of selfishness is that she didn't encourage Old Nick to take Jack outside as soon as he was bornnote presumably abandoning the newborn at a hospital, rather than...y'know... because in her isolation and loneliness, she desperately needed love. When everything else she's endured doesn't break her, being reminded of the only thing she's done for herself in seven years, and what that meant for her son, pushes her over the edge.
In the film when she's starting to plan the escape, Ma says to Jack that Room isn't on any map. When Officer Parker parses together a rough location from Jack's truck explanation, she calls it in, telling them where to look and adding to "also check the most recent satellite images for a red-pick up in the driveway." Room's most definitely on a map.
Jack's grandpa's attitude is this when you stop to consider that in many real-life kidnapping cases, the parents are almost always considered the prime suspect. So all that plus the trauma of not knowing if your child is even alive and then finding out she is but the knowledge of the horror she's been through... it gives you a glimpse of the absolute hell this man's life has been!
