In Magic the Gathering, what block is the Homelands expansion set?
Homelands was originally released as part of the Ice Age block, at least for tournament purposes. Because it did not fit with the themes or mechanics of Ice Age, it was later replaced with Coldsnap. So at this time, Homelands is not considered part of Ice Age or any other block.
From the MTG Wiki:

The Ice Age block is the first block of sets, consisting of the large expansion Ice Age in June 1995 and two small expansions, Alliances in June 1996 and Coldsnap in July 2006.
The Homelands expansion, released after Ice Age and before Alliances, was originally considered to be a member of the Ice Age block, although it included none of the mechanics or themes of the block.

And

Homelands, released in October 1995, is the seventh Magic expansion. It was the second expansion of Ice Age block until July 2006, when it was replaced by Coldsnap in this role.