So, my guess to Mab's human identity is none other than William the Conqueror's wife - Matilda.
Matilda was the first Anglo-Norman Queen of England, and was often referred to as Matilda, Mathilde, Mathilda, Maude, Maud. This is the same route as Maeve, Medb, etc.
She may also be Morgana by another name. But that doesn't explain how she got her Athame back, or why she didn't seem to recognise it as hers.
Titania is Nimue, the Lady of the Lake. Her historical name I cannot yet predict barring further insights.
I base this partially on historical accounts of those who rode with the Conqueror, and partially on the Merlin (1998) TV series in which Mab is the sister to the Lady of the Lake.
In the series, Uther (Arthur's father) is invading from Normandy and so I suspect somehow Jim will link Uther or Arthur with William the Conqueror.