Decades have passed, many things have changed, some things haven't and everybody she knew including her daughter has died of old age.
With her report of events dismissed and being made a scapegoat for the financial loss associated with the Nostromo, Ripley ends up doing low status work to scrape a meagre living. The planet where she encountered the Xenomorph is now a small colony and nobody has ever encountered anything like it there.
That is until one day her Company case worker Carter Burke (Paul Reiser) knocks on her door asking if she will join a mission there as a consultant. It seems they've lost contact with the colony...
No good will come of this.