誰が

誰 (dare, “who”) +‎ が (ga, nominative marker)

誰(だれ)が • (dare ga) 

1. Used other than figuratively or idiomatically: see 誰,‎ が.

誰 (ta, “who”, archaic pronoun) +‎ が (ga, nominative marker)

誰(た)が • (ta ga) 

1. (archaic) Synonym of 誰が (dare ga, “who”, nominative)

Old Japanese , from 誰 (ta, “who”, archaic pronoun) +‎ が (ga, archaic genitive marker). 誰 took the reading tare as a free morpheme, but ta if followed by ga. Compare 我が (a ga, wa ga, “my”) and 汝が (na ga, “your”).

誰(た)が • (ta ga) 

1. (literary) Synonym of 誰の (dare no, “whose”)

   誰(た)がために鐘(かね)は鳴(な)る

   Ta ga Tame ni Kane wa Naru

   For Whom the Bell Tolls

   (literally, “For Whose Sake Does the Bell Toll?”)

   • 2018, Mafumafu (lyrics and music), “朧月 [Hazy Moon]”:

     今宵は誰がために踊るのでしょう
     霞む　私は朧月
     手繰り寄せる　朱殷の糸口よ
     貴方に続けと願う

     Koyoi wa ta ga tame ni odoru no deshō
     Kasumu watashi wa oborozuki
     Taguriyoseru shuan no itoguchi yo
     Anata ni tsuzuke to negau

     For whom will I dance tonight?
     I'm a hazy moon that's growing dim
     The dark-red ends of the threads are reeling in
     I wish they'll connect me with you

   • 2019, Mafumafu (lyrics and music), “曼珠沙華 [Red Spider Lily]”:

     「来过来一下」
     そして心に背いて
     誰が為に芽吹くの？
     薄れずに 色味帯びていく
     憂いと彼岸の花

     'Lái guòlái yīxià'
     Soshite kokoro ni somuite
     Ta ga tame ni mebuku no?
     Usurezu ni iromi obite iku
     Urei to Higan no hana

     'Lái guòlái yīxià'
     Against the heart,
     For whom will it sprout, I wonder?
     Tinging with everlasting tones
     That is the lily of sorrow