With Steve vacating the B-Wormhole system, Melissa sees an opportunity to acquire a Wormhole. She needs to control both B-Wormhole systems to achieve her Secret Objective.
She doesn't want to appear to threaten Steve however. The easiest manuver would be to move the 2 Dreadnoughts next door into the B-Wormhole system.
When sitting that close to another player's Home System, and remember Steve does not know what her Secret Objective might be - there are Secret Objectives that include taking control of another player's Home System planets, moving in 2 Dreadnoughts might be seen as too aggressive and trheatening.
She decides instead to send in 2 Cruisers from "Vefut II".
Proceed to Nicholas.