I don't understand the trouble about that Mary had enough problems to overcome already, they are the main characters in this series, so off course a lot happens to them.
When Adam tell Mary she needs to come because there is a fire, she don't grab the baby (even when it is right next to her) and they both just walk away outside, not her or Adam think about the baby, so it is kinda her own fault, and she do suddenly remembers the baby is in bed and someone else go get her, and is trapped inside the fire, now there are 2 dead, what could had be prevented if Mary did not forget her baby. It is bad enough that Albert was smoking there, and now all those blind children are stranded where they had a good home.
When Adam tell Mary she needs to come because there is a fire, she don't grab the baby (even when it is right next to her) and they both just walk away outside, not her or Adam think about the baby, so it is kinda her own fault, and she do suddenly remembers the baby is in bed and someone else go get her, and is trapped inside the fire, now there are 2 dead, what could had be prevented if Mary did not forget her baby. It is bad enough that Albert was smoking there, and now all those blind children are stranded where they had a good home.