mtomeo, mice are mammals and have to nurse their young for a short period after giving birth. This mother-mouse has laid claim (the territorial imperative) to a certain amount of territory which includes the grill and she will defend it against all intrusion. Mice are quite prolific and depriving the mother-mouse of her nestlings will only provide her with time to produce more of the same.
To break the cycle, I suggest that you reclaim your territory by obtaining a cat or some used 'kitty litter'. You can place small containers of the latter strategically around the area to scare her off.
Hopefully this will help breaking the cycle without breaking your heart. You must have read some of James Herriot's books.

I would not call you any of those names. These little rodents are quite prolific and it is your space and you have to establish boundaries. Cat is probably a better suggestion . Recently on my way to work I saw a very old german shepperd walking on very unsteady legs, coming to a very busy street. It appeared this dog was on its own, and I could not let it get run over by a car. So I followed it around the block, the dog looked at me suspiciously a few times and eventually reached a driveway. It went down the driveway to a yard. I knocked on the door and an older woman came. I realized I have seen her in the neighbourhood before. I told her about the dog and she said it should not have been outside at all. It was a sixteen year old male. I can't tell you how gratefull she was this dog was safe. As a younger woman I might have shown some concern for other animals, now I go out of my way to help people and animals. The most satisfying thing in all this: my children have shown same care and consideration for life of others.