から grammar question

「あ、夜は春君の歓迎会をするからね。六花が直々に腕をふるって差し上げますから、楽しみに待ってなさい。」

I read this a while ago and the からね part in the first sentence was kind of bugging me. The context is - a guy moved into a cousin's house. The girl gives him a tour of the house and at the end she says that line.
Now, I would understand if there was some sentence before it so から could relate to, giving the "reason", but there isn't. It's just "Ah (i just remembered/so I don't forget..." kind of sentence. So I'm wondering if there's actually something omitted between から and ね because it's obvious, like - "Ah, we are doing a welcoming party for you tonight から (so you should attend/so be sure to attend)ね"

Or maybe I'm totally wrong about it, in that case, what is the exact nuance and function of that からね. I am aware that there would be no change in the English TL without it.

Any help would be appreciated.

Edit: I have a sub question related to this. In a lot of anime/manga there are those "tsundere" girls who say だからね！ all the time. I'm wondering if it's just used for emphasis like "you know!" and nothing is omitted there?

It's considered a sentence final particle which expresses the speaker's strong assertion / determination.

から
［接助］活用語の終止形に付く。
２ （終助詞的に用いて）強い主張、決意を表す。ぞ。「思い知らせてやる―」

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から［格助接助準体助］の意味 - 国語辞書 - goo辞書

But this usage is also from "because", as in 思い知らせてやるから（待ってろ）, 歓迎会をするから（来てよ）ね, 別に好きじゃないんだから（誤解しないでよ）ね, so your interpretation "something is omitted between から and ね because it's obvious" is not wrong.

Awesome, thank you for the clarification.