Teen Titans comes to an end with issue 43 (Jan/Feb 73), an issue that contains two stories, both by Bob Haney.
The cover story, by Saaf and Cardy, continues the supernatural trend of this book, as Robin, Kid Flash, Wonder Girl, Speedy and Lilith come to an house belonging to an old man, whose grandson is being tormented by demonic creatures. The Teen Titans see the monsters tossing the boy around on the roof, but the house creates its own barriers and traps to make it difficult for the team to intervene.
The Titans stick around to try to figure out what is going on, and each one falls prey to a supernatural trap, though they all manage to survive the attacks.
The old man explains that the problems started long before, while his daughter was still alive. At one point, she thought her son had died from a fever, but then found that the boy was alive and well. As the old man relates it, her daughter had been inclined to bury the child and pretend he was kidnapped, which is not a sign of rational thought.
Possibly because the whole story is so strange, the Teen Titans go hunting and find the actual body of the child. He had died, and been buried by his mother. The boy the grandfather was raising was a demon changeling. The old man kills his "grandson," and tells the Titans that he is making them his heirs. It's a super creepy ending for the series, and would be played on many years later in the Teen Titans saga in a Secret Origins annual.
Lilith's back-up series also comes to an an end, with a story by Ernie Chan. Lilith comes across a town where a woman is being sentenced to death for a crime, partly because she is a spiritualist. Lilith convinces the prison guard that she is the woman's daughter. Even though the woman has confessed, Lilith is sure she is innocent, and sets out to prove it.
The woman did have a daughter who was kidnapped as a child, so there is a possibility that Lilith is her child. Lilith exposes the actual killer, although the "mother" was working a con on the man who was killed, and isn't completely innocent. But she did not commit murder, so the other charges are dropped, I guess, and she goes free.
The woman also manages to find her real kidnapped daughter, amazingly quickly. But then, the story was coming to an end and there was little time for any complexity there. Lilith decides to abandon her hunt and returns to the Teen Titans, her true family. Mal Duncan appears in the final panel. I had thought his last appearance was in the previous issue, but that was just the last story he took an active role in.
After this the Teen Titans are not seen again, as a group, until the series is revived in 1976. Robin continues to appear in Batman books, and Kid Flash shows up in a couple of months in the Flash. Speedy returns the following year in the Green Arrow back-up series in Action Comics, although I tend to think that his drug addiction begins after the Teen Titans break up, so the revelation of that, in the previous year's Green Lantern story, would actually come after this one. There is no sign at all in these Titans tales of his drug use or recovery. Both Wonder Girl and Mal Duncan return when the Teen Titans series gets revived, but Lilith has to wait an additional year, returning as a member of Titans West.