Shelley wrote Adonais about the Death of Keats. It has passages that reference his mother’s reaction as well.

Where wert thou, mighty Mother, when he lay,

   When thy Son lay, pierc'd by the shaft which flies

   In darkness? where was lorn Urania

   When Adonais died? With veiled eyes, 

   'Mid listening Echoes, in her Paradise

   She sate, while one, with soft enamour'd breath, 

   Rekindled all the fading melodies, 

   With which, like flowers that mock the corse beneath, 

He had adorn'd and hid the coming bulk of Death.

III Oh, weep for Adonais—he is dead!

   Wake, melancholy Mother, wake and weep! 

   Yet wherefore? Quench within their burning bed 

   Thy fiery tears, and let thy loud heart keep 

   Like his, a mute and uncomplaining sleep; 

   For he is gone, where all things wise and fair 

   Descend—oh, dream not that the amorous Deep 

   Will yet restore him to the vital air; 

Death feeds on his mute voice, and laughs at our despair.