This looks the most likely index reference for her death certificate:

Deaths Jun 1900
Neath Edith 36 Peterbro' 3b 132

Unless you live locally, finding her burial will probably be a time-consuming and expensive business. The two most likely places for her burial would be the churchyard of St Margaret's Fletton (burial registers at Huntingdonshire Archives & Local Studies) and Fletton Cemetery (registers at the cemetery). You will need to pay for searches if you cannot visit these places yourself. There is no guarantee that she will be in a private, marked grave, nor is finding her burial likely to provide any genealogically useful information that will not be on her death certificate.