As user6726’s comment says, this has nothing to do with Hindi. Basque is a language isolate and not related to any other living languages, including Hindi.
It is possible to figure this one out, but it’s a bit tricky, because it requires making some assumptions that stray from what we’re used to in English kinship terms.
Note: I don’t know Basque, though I do know a tiny bit about its grammar. I did not look up any of the words. This is the logic I used:
The family tree and hint statements
Find commonalities in the statements:
- All statements are either
X Y-(r)en Z-a da or
X eta X Y-(r)en Z-ak dira. The logical conclusion is that that these mean “X is Y’s Z” and “X and X are Y’s Zs”; in other words, -(r)en marks a possessive, -a marks a singular subject complement1, -k marks the plural of nouns, da/dira is 3s/3pl of the copula ‘is/are’.
Find statements that only include people we know (no blanks). These are 5, 7 and 9:
- (5) “Inma Manuren arreba da” – since Inma and Manuren are siblings, this must mean “Inma is Manu’s sister”
- (7) “Iker Joseparen senarra da” – since Iker and Josepa are married, this must mean “Iker is Josepa’s husband”
- (9) “Manu Iboneren semea da” – since Ibone is Manu’s mother, this must mean “Manu is Ibone’s son”
So we have some words now: senarr[a] ‘husband’, arreb[a] ‘sister’, seme[a] ‘son’. So far so good.
- Find statements that use the words we know:
- (6) “Ibone eta Felix senar-emazteak dira” must mean “Ibone and Felix are husband-X”.2 The most likely thing to juxtapose with a husband is a wife, so let’s assume emazte[a] means ‘wife’ and together senar-emazte[ak] means ‘a married couple; husband and wife’ – first name placed (Felix is Ibone’s husband and Mikel’s brother)! This also shows that Basque makes use of dvandva compounding.
- (1) “Ines Mikelen emaztea da” – with the knowledge that emazte[a] means ‘wife’, this must mean “Ines is Mikel’s wife”; second name placed!
- (8) “Andres eta Ibone Emilioren seme-alabak dira” – similar to 6, this must mean “Andres and Ibone are Emilio’s son and X”, and here ‘daughter’ is the obvious candidate for alab[a] – third name placed (Andres is Ibone’s brother)!
So now there’s only one name left to place: Kontxi must be Mikel and Ines’ daughter, sister to Monika. We should be able to verify this by looking at the remaining statements, namely (2), (3) and (4):
- (2) “Mikel Felixen anaia da”
- (3) “Monika Kontxiren ahizpa da”
- (4) “Andres Iboneren neba da”
We now know that these all describe sibling pairs: “Mikel is Felix’s brother”, “Monika is Kontxi’s sister” and “Andres is Ibone’s brother”.
But wait, hang on. (2) and (4) both have ‘brother’, and (3) and (5) both have ‘sister’, but they use different words!
Mikel is Felix’s anaia while Andres is Ibone’s neba.
Monika is Kontxi’s ahizpa while Inma is Manu’s arreba.
How odd. They sort of look like pairs, anai[a]/ahizp[a] vs neb[a]/arreb[a], but what might the difference be? My first guess was that perhaps it was older/younger siblings, but since we have no way of knowing who’s older or younger, that would be pure guesswork, which seems against the spirit of the test.
My second guess was that Basque has different words for ‘brother/sister of a girl’ and ‘brother/sister of a boy’, or perhaps more accurately (to keep the pairings) that sibling terms in Basque are sensitive to whether you’re same-sex siblings or opposite-sex siblings. So anai[a]/ahizp[a] is ‘same-sex brother/sister’ and neb[a]/arreb[a] is ‘opposite-sex brother/sister’. This is unusual, but it fits the data given. Cheating a little and looking at the solutions, Kontxi is listed as being Monika’s ahizp[a] (which makes the older/younger distinction impossible – they can’t both be each other’s older sister), and Ibone is Andres’ arreb[a], so everything fits.
Vocabulary and solution statements
So now we know that Basque uses dvandva compounds, and we have the following vocabulary (assuming root forms in accordance with note 1 below):
anai(a?) ’same-sex brother’
ahizpa ‘same-sex sister’
neba ‘opposite-sex brother’
arreba ‘opposite-sex sister’
Filling in the solution statements now becomes quite easy overall.
The only thing left to figure out is why (b) has alaba-semeak when (8) has seme-alabak. The reason here presumably has to do with the order of the names and the nature of dvandva compounds. If you think of it as meaning ‘X and Y’, it stands to reason that Andres (male) and Ibone (female) would be seme-alabak ‘son and daughter’, while Inma (female) and Manu (male) would be alaba-semeak ‘daughter and son’.
On the other hand, Ibone (female) and Felix (male) are senar-emazteak ‘husband and wife’ in (6), so this principle clearly doesn’t apply all the time.
So to answer the crux of your question: based solely on the data given, you indeed could not have known that (b) needed a reversal of the two parts of the compound compared to (8), because (6) messes up the neatness of the logic that dictates that it should.
1 Or something like that. The -a doesn’t seem to appear in compounds, at least not after vowels, so it’s probably a case ending, not part of the root. In the solution to b), though, we see alaba-semeak (not *alab-semeak), so perhaps it’s rather that roots ending in consonants (seemingly excluding at least r, as in senar) get a euphonic -a which merges with the case ending -a. No way to tell just from the test here, but I’m just going to assume that the -a only disappears after vowels and r in the lookup form.
2 There’s an extra r in senarra when it appears on its own; this is perhaps regular, perhaps irregular, but it seems unlikely that senar- and senarr- should be different words in an exercise like this.