Visual and auditory hallucinations in the elderly

I have an elderly neighbor, she’s well over 70, and she’s dealing with something quite strange. Occasionally, everything in her room suddenly appears tinted red. On top of that, she starts seeing red objects that aren't actually there—things like red mushrooms or red hearts.

Then there is this other thing: for a few years now, whenever she finally settles down, say when she's sitting quietly or getting ready for bed, she hears singing in her head. It sounds like the old folk music from her youth, or even her own voice singing songs she never actually learned.

Aside from that, she’s perfectly fine to talk to, though her hearing isn't what it used to be, which leads to some occasional misunderstandings in our conversations.

The doctors have mentioned it's a brain-related issue, but they haven't given us a specific diagnosis yet. She did go in for some brain scans.
They prescribed her Meredith.

Anyway, does anyone here have any insight into what this might be?
And if this condition continues to progress, what should we realistically expect in the future?

She is also currently taking several other medications: Diazepam (for muscle spasms), Advil (for her rheumatism and bone issues), and some pills for her blood pressure.

Michael Mitchell10 said:An elderly neighbor of mine, she's over 70, is dealing with something strange. Sometimes everything in her room just looks red to her. She’ll also see red objects that aren't actually there—stuff like red mushrooms or red hearts, etc.

For a few years now, she’s been hearing singing in her head when things quiet down, like when she's sitting still or getting ready for bed. It sounds like old folk music from back in the day, or even her own voice singing songs she never even learned.

Otherwise, she talks to me normally, though her hearing isn't great, so I think she occasionally misinterprets what I'm saying.

The doctors told her it's a brain issue, but they haven't given a specific diagnosis. She already had some brain scans done.
They prescribed her Meredith.

Anyway, does anyone know what this could be?
What should we expect in the future if the condition keeps progressing?

She's also taking these: Diazepam (for spasms), Advil (for rheumatism and bones), and blood pressure medication.

This sounds like typical geriatric dementia, which explains why they put her on Meredith. Honestly, looking at her current meds, those hallucinations might actually be triggered by them—especially something like Diazepam.
As for what's coming next? You're likely looking at continued mental decline. My hope is that she has her affairs in order for when the time comes that she can't look after herself anymore, because that's where this goes for a lot of people. If she doesn't have that support system, you need to be prepared to call social services once you realize she's hit that stage.