Ella:
none, because
Ella is so common and boring, but if it must be used then I'd go with
Elena or
Elaine.
Lily:
Lillian
Lia:
none, because
Lia is a full name and I like it much better on it's own, especially spelt
Leah. If I had to use it as a nn, then for
Amalia
Emmy:
Emmeline, because it is the least used and has that great namesake
Emmeline Pankhurst.