It might also be a symbol of temptation. Lemons are often associated with freshness and vitality. For vampires who are undead, the lemon grove could be a source of both allure and frustration. They may be drawn to the life around them but unable to fully partake in it. Additionally, the grove could be a place of change. As the lemons grow and are harvested, it shows a cycle of life that the vampires are on the outside of, yet still affected by.
The story 'Vampires in the Lemon Grove' might explore themes like the struggle between immortality and the mundanity of life. Vampires, usually associated with mystery and power, are placed in a lemon grove which is a rather ordinary setting. This contrast could be used to show how even the extraordinary can be trapped in the banal.
The presence of vampires in the lemon grove could be a metaphor for the intrusion of evil or the unknown into a peaceful and familiar place. It could also be used to create tension and suspense in the story.
In 'In a Grove', the multiple perspectives create a sense of mystery. Each character has their own version of the events, which makes it hard to figure out the 'true' story. For example, the bandit, the wife and the samurai all have different accounts of what happened in the grove. This shows the unreliability of human perception and memory.
The bandit in 'In a Grove' is portrayed as a rough and bold character. He seems to be unafraid to take what he wants. The wife is more complex. She may be seen as a victim, but her own account of the events makes us wonder about her true nature. The samurai, though dead, has his own perspective too, which shows his pride and sense of honor even in death.
I'm not sure without reading the story specifically, but it could be a lost traveler. A lost traveler in the grove would make for an interesting main character as they would have to face the unknown and try to find their way out.
The main theme could be mystery. The grove setting often adds an air of mystery as it is a secluded and somewhat eerie place. Things might happen there that are not immediately clear, like strange noises or unexplained events.