Beacon of Hope says:
... Choose any number of creatures within range. For the duration, each target has advantage on Wisdom saving throws and death saving throws, and regains the maximum number of hit points possible from any healing.
And then Vampiric Touch says:
... On a hit, the target takes 3d6 necrotic damage, and you regain hit points equal to half the amount of necrotic damage dealt.
Emphasis mine.
If Al casts Beacon of Hope, and targets Bob, and then Bob casts Vampiric Touch, is the healing maximized as if he had dealt maximum damage?