Does anyone knows who are the leading economists in the field of elderly and intergenerational transfers?
I'd like to know what are the current topics they are working on.
A few suggestions.
There is a rather old Handbook of Population and Family Economics, edited in 1997. But it is certainly a good introduction. There are several chapters which might be of interest. For instance, Chapter 11, named "Mortality and morbidity among adults and the elderly", or Chapters 16 and 17 about aging.
A very recent (Nov 2016) Handbook of the Economics of Population Aging, which also includes chapters on aging, intergenerational issues, longevity, pensions. For instance, Chapter 8 about "Insurance Markets for the Elderly".
You can look up latest papers on any topic by using JEL codes. In your case, take a look at J14, J26, J62. To look up working papers and published papers, use the IDEAS service. For instance, J14 papers here. You can see around tenth in the list there is this paper, called Subsidy Policy and Elderly Labor, released the 21st of December of 2016. You cannot beat IDEAS repository!
Finally, if you want to be updated with the latest research, subscribe to weekly emails of your topic of interest using the New Economics Papers tool of IDEAS. Find it here. You would be probably interested in NEP-DEM.