I concede. You can put a feminist interpretation on Beowulf! You might also say that the "true" religion (Christianity) was defeating paganism when Beowulf killed Grendel's mother. Hey, and the dragon is a religious symbol too. The serpent (a dragon is a serpent with wings) symbolizes Satan.
When students ask us why they have to read something so old, we have a lot to say!
I like your explanation very much, linda-allen! I agree that the goddess centric cultures would go far to explaining the nature of the mother. However, I would argue that a feminist interpretation would accept this connection as more proof of her importance. That interpretation might say that she, like the goddess' in those cultures, represents the natural matriarchal leader; and being cut down by a warrior represents the death of female power in the face of patriarchal societies.
I don't like to put modern interpretations on ancient texts; those writers didn't think of terms of "isms" but just described the world as they saw it. That having been said, you might think of Grendel's mother as a throwback of the mother goddess cult. She lived in an underground cave; in the mother goddess cult, caves were the places of worship, symbolizing the mother's womb. She controlled the elements, another aspect of the mother goddess. Maybe the movie producers should have had Rosie O'Donnell play Grendel' mother instead of Angelina Jolie!
It would certainly include the power she has over her environment. She is the matriarch and the queen of her kingdom. The beasts and the water respond to her. She is more powerful than her son.
And yet, she is defeated. What is interesting is that she is defeated by the instruments of society. She can not pierce Beowulf's armor, a symbol of the human world. In contrast, Beowulf can not fight her barehanded, suggesting that in nature she has the most power. But when he uses a sword, another object of human social development, he is able to conquer and defeat her.
The message is that women are naturally more powerful, but the restraints of society have weakened them to a point of subservience