Late season swarm?

[ArmucheeBee]

During the 4-5 inches of rain this morning, we were out looking at the flooding.  My daughter found a small cluster on the ground under one of our 6 hives.  I scoooped them up and put them back on the porch and found a new fresh queen (not marked).  This hive had no Q-cells on Sep 27 as I did my fall check and downsizing.  Saw none in the other hives last week either.  So she may have come in to our yard which would mean a feral as no one else within 5 miles has bees!!  What is the best method to keep her alive until next season?  I know I have seen some info on keeping a queen in the top of a hive during the winter.  Is that using a Q-excluder below her?  Like a two Q hive?