I have an interesting connection of sorts to the "Slocum". My grandmother Anna (when a school girl) had a friend who was looking forward to the excursion. But the friend got sick, so she and her family stayed home. Grandma visited her and tried to cheer her up. As they were talking, they heard screams outside from the street from people who saw the "Slocum" burning up. Because her friend missed the trip, she and her family were not among the dead.
From memory, missing, never found, but I will need to check.
So many stories like your grandmother's I had a similar one myself (that I'd rather not post about here) that is the only reason I'm alive today.
G U T
There are two ways to be fooled, one is to believe what isn't true, the other is to refuse to believe that which is true.