I'm with nsx, what you describe is in no way how WN's VDB process works, I think your mother may have misunderstood what was said because it is so inconsistent with WN's process. First, they always offer a variable amount, and second, I don't think they would ever offer just $50 ($0 award ticket value + $50 for VDB). In fact, to me it sound like she was offered a $50 value plus $200, getting to the $250 she received.

Note that the $50 value sometimes allowed award tickets is not WN policy, Brian has indicated official policy is that the value is $0, but some gate agents do it for $50 contrary to official policy.