What denomination is this?
Her beliefs are simply not scriptural.
Tell her to read the New Testament instead of the national enquirer.

Because Jesus is eternal God, who unites all of us (including Mary) to Himself in His death, burial, and resurrection.
We
died with Him !! (It is really true!!! )
We are
risen with Christ!! (It is really true!!! )
We
live with Him !! (It is really true!!! )
Mary can’t & couldn’t do any of that. Mary’s continued life is centred on Jesus: the blessed fruit of her womb, Her Saviour, her son.
from the Protestant NIV: Colossians 2:
4But because of his great love for us, God, who is rich in mercy, 5made us
alive with Christ even when we were dead in transgressions—it is by grace you have been saved. 6And God
raised us up with Christ and
seated us with him in the heavenly realms in Christ Jesus, 7in order that in the coming ages he might show the incomparable riches of his grace, expressed in his kindness to us in Christ Jesus. 8For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— 9not by works, so that no one can boast. 10For we are God’s workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do.
BTW, protestants can poorly teach their people too. so it is best to not characterize her apparent lack of knowledge as a general characteristic. (Personally, I thought it an evangelistic ploy on her part to attack what she sees as the over veneration of Mary.)
here’s another passage: from Romans5
6You see, at just the right time, when we were still powerless, Christ died for the ungodly. 7Very rarely will anyone die for a righteous man, though for a good man someone might possibly dare to die. 8But
God demonstrates his own love for us in this: While we were still sinners, Christ died for us.
9
Since we have now been justified by his blood, how much more shall we be saved from God’s wrath through him! 10For if, when we were God’s enemies, we were reconciled to him through the death of his Son, how much more, having been reconciled, shall we be saved through his life!
and from this we see how the obedience of Faith is related to the eternal sacrifice of the living Saviour generously pours out His Grace into our lives.
His Mercy and Grace is freely poured into our lives by the Holy Spirit through a life of walking with God & through the means of grace that He has appointed for us in that walk of obedient faith.
That free grace gives us hope. and her too. That is why the Savior really needed to be God
wayne