Her marriage to Dr. Thomas Delano took place before October 30, 1667. At that time the Alden and the Delano family seem to have been neighbors. The Delano's had nine children: Benoni, Thomas, Deborah, Jonathan, David, Mary, Sarah, Ruth, Joseph.. The Delano family resided at Duxbury. Thomas Delano outlived his wife, who seems to have died in the time period from 1696 to 1722.
It is claimed that Rebecca died before 13 June 1688, the date her father's estate was settled. Is this correct? Her husband Thomas Delano signed the probate document, but so did William Pabodie, and no one is claiming that Elizabeth died before that date. Two other husbands signed but they clearly state in the right of their deceased wives.
Other suggested Dates: 12 Sept 1688, April 1723, 13 June 1688, after 13 Jun 1689
Rebecca was alive 12 June 1696 (when she was called a motherly woman) and died before her husbands will 5 Oct 1722. She is probably buried at the Myles Standish Burial Ground in Duxbury.
Source: Title: Records of the Colony of New Plymouth in New England, Nathaniel B. Shurtleff and David Pulsifer, eds., 12 volumes in 10 (Boston 1855-1861)
Source: Woodworth-Barnes, Esther Littleford and Williams, Alicia Crane, Mayflower Families through Five Generations, Vol 16 Part 1 of 3, John Alden, Boston, Mass.: General Society of Mayflower Descendants, 2002.
Mayflower Births and Deaths, Vol. 1
Source: Title: Family Data Collection - Marriages Author: Edmund West, comp. Publication: Name: Name: Online publication - Provo, UT, USA: The Generations Network, Inc., 2001.
Source Title: U.S. and International Marriage Records, 1560-1900, Author: Yates Publishing, Online publication - Provo, UT, USA: The Generations Network, Inc., 2004. Original data - This unique collection of records was extracted from a variety of sources including family group sheets and electronic databases. Originally, the information was derived.
Source: Information from the Alden Kindred website 
Thanks Charles Seamon, K Bris, Regina DeMarco, Stephen Wilkinson, Bob Carson, Tom Elliott, Michael Stephenson, Mike Walton, Ann Fuller, Bob Carson and apologies to those missed. Lots of work in change log. Click the Changes tab for the details of contributions.