This is much better but you're having a problem with dialogue. Let me give you a quick example.
Code:
Christopher walks over towards Granddad.
GRANDDAD
Stop it! Please stop!
Christopher rocks Granddad by the shoulders, but Granddad
remains in pain.
VOICE (V.O.)
You’re all alone.
GRANDDAD
[COLOR="Blue"]These voices... it won’t stop![/COLOR]
Christopher takes Granddad’s hands away from his ears and
holds them in front. He stares at Granddad, who tears.
GRANDDAD
[COLOR="Blue"]There’s a ghost in my head. It won’t leave me.[/COLOR]
Christopher shakes his head. Granddad sees this and
CRIES.
Granddad's dialogue has a couple flags for me. "These voices" suggest more than one, then he says "it", "a ghost" suggesting one voice. The viewer 'hears' one voice. Be consistent. Is it one voice or many. The next flag is granddad responding to Christopher but not the voice. In these cases, a person experiencing a psychotic episode would be responding to the voice predominantly. Often what is not said is as powerful as what is.
Code:
Christopher walks towards Granddad, who sits on the bed,
rocking with his hands on his ears. Granddad glances
towards someone not there.
GRANDDAD
Stop it! Please stop!
VOICE (V.O.)
You’re all alone, old man.
Christopher hesitates then walks over to Granddad and rests
a hand on his shoulders. Granddad looks at him startled.
Christopher takes Granddad’s hands away from his ears and
holds them in front.
Granddad looks saucer-eyed at Christopher.
GRANDDAD
There’s a ghost in my head.
He stares at Granddad. A beat. He shakes his head and
sighs. Granddad sees this and cries.
You have an opportunity for character development through visuals. I'd start that from page one. What is seen often more important than what is said. Films are very Gestalt. Help us feel it with the granddad by describing what we see. Don't say it. Show us how he's suffering, don't say it.
Code:
Christopher lets go of Granddad’s hands and exits the
bedroom...
GRANDDAD
(to himself)
Why? Why won’t you leave me?
VOICE (V.O.)
Because I want you to suffer.
GRANDDAD
(to himself)
You’ve made me suffer enough. I can’t live a
day in peace because of you.
VOICE (V.O.)
Good... that is what I want.
GRANDDAD
(to himself)
I don’t want it... please... I beg you... stop this
now.
Voice LAUGH.
Since he's alone, it's obvious that it's to himself, you don't need to include the parenthetical. But more to the point, this dialogue is too expository and on-the-nose. Good dialogue hints and uses the audience's experience to fill in the gaps.
Code:
Christopher hears action on the television and gets
impatient. He shakes his head and lets go of Granddad’s
hands. He goes to the door, glances back then exits the
bedroom.
GRANDDAD
Just a day. Please. Why can't you leave me--
VOICE (V.O.)
alone in the silence? Do they know the
truth? Those dark secrets, the fear, the ...
GRANDDAD
Please. I beg you.
VOICE (V.O.)
... madness inside? It's just us now.
Grandad pulls the pillow over his head while the laughing
voice echoes around him as he thrashes.
You've done a good job. Just subtle tweaks to the action statements will allow you to pare back expository dialogue and add dimension to the characters and the scene. I really like the way you follow up with Christopher giving him the medicine. As a clinically trained therapist, I've worked with individuals who have voices and delusions. The voices often speak, not just spit out words. Rather than have it repeat over and over "Crazy. mental. delusional. lonely. madness. hated. insane. etc." give it messages. My advice is the VOICE IS A CHARACTER TOO. For schizophrenics, these voices are separate personalities. Use the voice to coax, cajole and manipulate granddad. It reacts to Chris because it feels threatened.
Don't have granddad repeat everything that voice says. Only one of them needs to say it. DON'T REPEAT what's already been said. We know granddad wants it out and can't take it. Let them have conversations. Shift to describing it visually and let the Voice give some varied messages. Silence is powerful. DON'T DO VOICEOVER WITH GRANDDAD! The message will be more powerful if the Voice is the only voiceover. You need to trust me on this. Since granddad (and audience) hear the voice as VO, having his own voice as VO will really confuse the audience.
Stylistically, you overuse caps. Laughter is a natural response. It doesn't need caps anywhere in your script. CAPS should be used very sparingly. And some readers would prefer you not use them at all. There are no firm rules. However, in your script, there is nothing that justifies using them. Your sluglines should include the time of day: INT. KITCHEN - NIGHT.
I think this second version is much better than the first and has shown really good choices and development. I don't mean to sound critical. I want to emphasize that so much of this story is carried by the visuals, actors and the character of the Voice so the dialogue needs to be clean. That final dialogue really needs to be powerful, and right now it feels muddy. In writing dialogue, less is better. As you balance dialogue and action, the pacing should adjust. It drags a bit due to the unevenness.
Overall, I feel you did a good job. You have a good feel for story. It has the makings of a good short as it has evolved. It shares aspects of de Maupassant's "The Horla". Good luck!