im wondering, the sevara of Kivan d'Tekinu Rabanan l'Meimar Hachi etc., is it because solely since the rabanan said so, or there has to be a connection to tefila or geulah in what is being said.
Marcus Abisror, Lakewood
The Ritva says that Hashkiveinu deals with "Ge'ulah mi'Shedim v'Chol Davar Ra." Rabeinu Yonah (2b in the Rif) states that in the night of Yetzi'as Mitzrayim the Jews were praying to Hash-m to save them, and this is comparable to our prayers in Hashkiveinu. So according to these explanations, Hashkiveinu actually is about Ge'ulah. The Rashba (Teshuvos #51, cited here by Rebbi Akiva Eiger in the Gilyon ha'Shas; see PDF) seems to imply that the addition of Hashkiveinu was in order that we recite seven Berachos a day around Keri'as Shema, as the verse says, "Sheva ba'Yom Hilalticha" (Tehillim 119:164). He does not address how this has a connection to Ge'ulah, implying that such a direct connection is unnecessary. As such, it seems to me that both sides of your question are correct and it is a Machlokes between these Rishonim if Hashkiveinu is relevant to Ge'ulah or not.
Shimon Brodie