But what motivation do the Separatists have for attacking the Larses? I don't think they even know Anakin has any connection.
If it's from the new film, more likely it has to do with Jabba's henchmen.
Actually, if you believe in the possibility that Count Dooku was the driving force behind the Tusken Raiders kidnapping Shmi Skywalker-Lars then there is a chance that Dooku actually knows the significance for the Lars family to Anakin - even if it's just from Darth Sidious instructing Dooku to arrange for Tusken Raiders to kidnap and torture a woman on Tatooine named Shmi Skywalker - when Dooku's operatives find out where she is, for all Dooku knows, Cliegg is Anakin's father and Owen is Anakin's brother. Dooku might be going to Tatooine to outright kill what he perceives is the rest of Anakin's family.
I have two guesses for this set:
1) ANH - Either a Dewback and 2 Sandtroopers or Luke and the updated Sandspeeder, the main dome structure with fire damage and two skeletons.
2) All new sculpts to support the short story in the Visionaries TPB.