What is "jubilee(s)"? My Mother in her 90s and in treatment for Alzheimers would frequently go into a state of trance and chant about going to jubilee.

Does "jubilee" or "going to jubilee" refer to heaven or eternity in Christianity?
In the Hebrew Bible, Jubilee refers to a set of practices around forgiveness of debts and restoration of land. Basically, every 7 years the people were supposed to hold a "sabbath" for the land and rest from farming. Then in the 50th year (the year after the 7th Sabbath/Sabbatical Year), all land ownership was supposed to resort to it's original tribes/clans/families, all debts be forgiven, all slaves set free, and a general year of celebration and festivity observed. This was known as the "Jubilee Year." See Leviticus 25 for a description of how this was supposed to work. 

It's not originally a description of heaven, but it's an image a lot of later Biblical writers would use to describe "heaven" or "the kingdom" or "salvation" and other similar concepts. For example, Isaiah 61 talks about the deliverance of the people by God as the "year of the Lord's favor" when the captives are set free, the cities rebuilt, and the people are too busy celebrating to tend their own flocks, which sounds a lot like the Jubilee year. So Jubilee takes on more meaning as an image of what heaven is supposed to be like.