Popped along to the Museum and although I found Isabella Corlett aged 55 years, buried in Kirk Onchan 16 July 1902, there wasn't any monumental inscription record there.
So off I went to the cemetery and had a word with the S extant there, who said I needed to have a word with the Parish Clerk, Jane Cretney

Unfortunately, Jane was out and I'll pop along to see her when she's in and take a photo of the grave position names & numbers to locate Isabella and get back to you when I can.

I can say however, that the grave will be in the right hand section if facing the church from the road, as the rest is classed as the 1928s upwards, however some graves are family graves which hopefully yours isn't among them.
If the grave is unmarked, I'll locate it and put some type of marker onto it, so you'll know for when you do come over.

Best wishes,
Paul