Hey Ren, want big sis to hold your hand for you? You always wander off every year, after all.
Literal
Hey Ren, older-sister [subject-が] hand [obj-を] connect-[do-for-you-てあげよう] [question-か]? You [topic-は] every year, soon get-lost-[regrettably-ちゃう] [because-もん-ね].
A concerned older sister. 手をつなぐ ('to hold hands, to connect hands') is the fixed phrase. ~てあげようか ('shall I do X for you?') is the suggestion form of the giving auxiliary. はぐれる ('to get separated from, to be lost from a group') is distinct from 迷う ('to be lost'). もん is casual contraction of もの, giving the 'because, you know' generalizing sense, combined with ね for friendly rhetorical emphasis.