I was trying to look for some information for you in the book "The Libby Family 1601-1881 by Charles Libby Esq.
On page 130 of the book there is reference to a Meshach Libby that was said to have been born possibly in Rye NH. He marriedDeborah Ely.He was said to have been the first settler of Porter, Maine. He also is said to have lived in Chichester, and Parsonsfield, Maine and Pittsfield, New Hampshire. He settled in Porter in 1781. Meshach died in Porter, Maine in March of 1829.
There is more info on his life if you are interested. Anyhow, his wife Deborah died in 1795 and he then married second a widow by the name of Hannah (Cram) Elkins. Possibly this is the Hannah and Meshach Libby that you are looking for.
There were six children born to Meschach and Deborah:
Sarah Mary Meschach Elsie Elizabeth died in childhood. Eunice
If you think that this is the family that you are looking for let me know and I will give you further details.
The reference number in the Libby book is 6-4-1-2,
Meschach was the son of John and Eleanor (Berry) Libby