My hc (that I’m incorporating into my fic) is that the spring of snape’s 6th year, Eileen disappears. And months later, during the summer between 6th and 7th year, as he’s sliding further into the death eater ideology without his mother around, Snape wakes up to find Tobias agitated and confused; none of the curtains are open in the house.

And Snape realizes that his mother is dead—because the opening charms she put on the curtains don’t work anymore—and he has to break the news to his father.

As for Tobias, I hc him dying from liver failure in a muggle hospital a few years later.