Learn Hardcore Hausa: Yara suna son jin labaran kaka da daddare. - The children like to hear grandmother’s stories at night.

Hausa normally does not use a separate word for the or a.
Yara simply means children; context tells you whether it is the children (specific group) or children in general.

In this sentence, you can understand it as either:

The children (some particular children we know about), or
Children in general (a general statement about kids).

Why do we say suna son instead of just suna so?

So is the verb to like / to love / to want.
The form normally used after suna (or any aspect marker) is the verbal noun so̱ → son when it links to another word.

So:

suna son … = they are in the state of liking … / they like …

Using suna so is not the usual pattern. In standard Hausa, you say:

Ina son shayi = I like tea.
Suna son wasa = They like playing.

So suna son is suna (they-are) + son (liking), not a mistake.

What exactly is jin doing here in suna son jin labaran kaka?

Ji is the verb to hear / to feel / to sense.
Jin is its verbal noun, meaning hearing / the act of hearing.

The pattern is:

son jin X = liking (the) hearing of X → liking to hear X.

So suna son jin labaran kaka literally has the structure:

they-are [in a state of] liking [the] hearing [of] grandparent’s stories
= they like to hear grandma’s stories.

What is the difference between labari, labarai, and labaran, and why is labaran used?

labari = a story / news / report (singular)
labarai = stories / news items (plural)
labaran = the stories of … / stories belonging to … (genitive/possessive form)

Labaran is the plural labarai plus the genitive ending -n, which links it to the next noun (kaka):

labaran kaka = the stories of grandma / grandparents’ stories

So labaran is used because the stories are possessed/associated with kaka.

Does kaka mean grandmother or grandfather, and whose grandparent is it?

Kaka is a kinship term that can mean:

grandmother,
grandfather,
and sometimes more generally grandparent / ancestor, depending on context.

In this sentence, there is no possessive pronoun (like kakata = my grandmother, kakarmu = our grandmother), so kaka is just grandma / grandpa / grandparent in a general or understood sense.

Context (or extra words in a larger conversation) would tell you whether it is specifically grandma, grandpa, or just grandparents in general.

Does labaran kaka mean grandma’s stories or stories about grandma?

Grammatically, labaran kaka simply means the stories of kaka (stories associated with the grandparent).

That can be interpreted as:

stories told by grandma, or
stories about grandma, or
stories that belong to grandma / are connected with grandma.

In everyday usage, many speakers will understand labaran kaka here as the stories (that) grandma (usually) tells. If you specifically wanted stories about grandma, you might make it clearer with extra words (for example, labaran game da kaka – stories about grandma).

What does da mean in da daddare? Is it and or at?

The word da is very flexible in Hausa; its core meaning is and / with, but it appears in many fixed expressions.

In the time expression da daddare (or da dare / daddare), da is best understood as at:

da daddare = at night / in the night-time

So in this sentence, da daddare functions as a time phrase: at night.

Is daddare the same as da dare?

Yes, they are closely related.
Historically/underlyingly:

da dare = at night (literally with night).

In fast, natural speech, da dare often becomes daddare. In writing you will see both:

da dare
daddare

Both mean at night / during the night, and in this sentence daddare is just the fused form.

Why is it suna and not yana or another form?

Hausa changes the subject pronoun according to person and number:

ni → ina (I am …)
kai / ke → kana / kina (you are …)
shi → yana (he is …)
ita → tana (she is …)
mu → muna (we are …)
ku → kuna (you plural are …)
su → suna (they are …)

Yara is plural (children), so it takes the they form suna:

Yara suna … = The children are …

Using yana would be for a singular masculine subject (he / it), which would not match yara.

Could I say Yara suna jin labaran kaka da daddare instead? What would change?

Yes, you can say:

Yara suna jin labaran kaka da daddare.

That means the children are hearing / usually hear grandma’s stories at night, focusing on the activity of hearing, not on liking.

The original sentence with suna son jin expresses liking or enjoying hearing the stories:

suna jin = they are (actually) hearing
suna son jin = they like to hear / they enjoy hearing

So your version loses the idea of liking and just states the action.

Is this sentence talking about a habit, something happening right now, or just a general fact?

With suna son plus a verbal noun (jin), this structure very often expresses a habitual or general preference:

Yara suna son jin labaran kaka da daddare.
= Children like / usually like / generally like hearing grandma’s stories at night.

It can theoretically be present progressive (are liking now), but in natural usage English would translate it most often as a general preference or habit, not a one-time event.