There's kind of three aspects to being a MILF, and whether or not someone's MILF itch is scratched really depends on which of these 3 aspects a person finds titillating:
1) Being Older
2) Looking Older
3) Actually being a Mother in the human sense.
At 70, Sharon ticks off (1) but not (2) or (3).
Laurie ticks off none of them.
Carmen doesn't tick off either (1) or (2), and probably doesn't tick off (3) either.
At at least several hundred and possibly over 2000, Calisto checks off (1) , but probably not (2) as she doesn't look more than 30, maybe a very hot 35. Whether or not she had any children back in her human days centuries or possibly even millenia ago is unknown. She's the MC's vampire mother however, does that count?
Dreamgirl is even older than Calisto, and almost certainly thousands of years old, but she looks like a teen, and again, whether she ever had a human child is unknown.
Astrid probably checks off (1), but doesn't look more than 25, and whether she's ever had children is unknown.
Olivia checks off (1) and (2), with (3) being unknown. She's a side character though.
The feral Nos checks off (1) and (2) with (3) being unknown and unlikely ever to become known or relevant as she's now dead.
And the list goes on, but the vampires typically check off (1), but not (2) or (3), and aside from Olivia the human women we've met check off none of them.
EDIT: I missed Miri. We don't know her exact age, but she looks like she's in her 20's and has multiple children. So Miri is the only character we know of that ticks off (3), but she doesn't tick off (2), and very likely doesn't tick off (1) either.
