Mina asks to see Renfield, and Dr. Seward allows it.
Renfield is very polite to her. He advises her not to stay in Dr. Seward's house during her visit to London, but won't tell her why.
Afterwards, Van Helsing joins them again.
He thinks "Madam Mina" is the awesomest woman in the world. He even compliments her so far as to say she has a "man's brain."
Mina's Journal, September 30
That evening, they have a meeting in Dr. Seward's study.
They discuss the kinds of power that they're up against: Dracula can control the weather, as well as animals (like rats, bats, wolves, etc). He can also vanish into a cloud of dust, and has incredible physical strength.
They all agree to work together to kill Dracula.
Van Helsing reminds them that they have science and technology on their side. Plus, Dracula loses his supernatural powers during the day.
(You should note that Dracula can walk around in the sunlight. The idea that sunlight can kill a vampire doesn't originate in the novel Dracula, but in the movie Nosferatu (1922). Stoker's Dracula is totally cool with the sun, but he can only change shape at nighttime.)
And they have lots of anti-vampire weapons, like garlic, crucifixes, holy water, etc.
Quincey Morris excuses himself from the meeting for a moment to go take a pot shot at a bat that was sitting on the windowsill.
Their next task is to find all fifty boxes of earth that Dracula shipped to England, and either kill Dracula if they find him, or at least "sterilize" the dirt by putting holy water in it so that he can't sleep there again.
Dracula can only sleep in the earth he brought with him from Transylvania.
Even though it's late now, the men decide to go check out Dracula's lair in Carfax house next door.
They tell Mina to go to bed and wait – this is a man's job.
Dr. Seward's Diary, October 1 at 4am
The men are about to leave the house when Seward gets a message that Renfield wants to see him right away.
The men all go to him.
Renfield acts totally sane, and begs to be allowed to leave.
They ask to know why, but he won't tell them.
They don't agree, but say that they'll revisit the issue in the morning.
Renfield shrugs and basically says, "Don't say I didn't warn you."