EDIT: Now that it's clearer that you're asking about the 選べ rather than the 来れば, ignore the next paragraph and skip to the end.
While え-form can indeed imply imperative, if it's ～えば then that's a provisional ("if") form, i.e. it means "If you came to my place ..." and in this context it's probably been contracted from 来ればいい, which is used to offer a suggestion. Sort of like "Wouldn't it be good if you ...?" or "You could always ...".
The 選べ is not an imperative え-form. It is, in fact, part of a conditional negative potential form. Specifically:
選ぶ (choose) → 選べる (can choose) → 選べない (can't choose) → 選べなかったら (if [you] can't choose)