This comes from Mike Memoli, the pool reporter at the service:
The VP has been a constant presence in the receiving line, as has Dr. Biden, even as members of the honor guard standing on either side of the casket rotate in and out. Other Bidens have been ducking out from time to time, but Hallie Biden, Beau’s wife, and the VP’s other son, Hunter, have been also logged considerable time....The receiving line was scheduled to run until 5 p.m. but pool is told VP will likely stay until the crowd stops coming.
A funeral mass for Beau Biden will be held Saturday in Wilmington. President Obama is scheduled to deliver a eulogy.