Fran,
It's only cos mine had no actual will that there was nothing. Original wills and letters of administration 1858 - 1900 were destroyed but the "copy will books"survived. So if there was a 'will' you will be able to get the info from it.
Re death 1890, as per post from Derrylass, it is worth contacting Letterkenny Registrar Office as the local offices are more willing to search name variations and over a period of time than GRO.
Kind regards
Angela