Her mother had been a wash maid at Vermentino and, as a child, Matilda always dreamed of running the vineyard one day. When her mother brought her to work with her, Lady Vermentino would always feed Matilda grapes and Matilda would briefly wish she was her real mother instead. In a sad way, she got her wish when her birth mother passed away and, having no children of their own, the Vermentinos took Matilda in.
Later on, when she was running the vineyard, a rivalry sprung up between her and Liam de Coronata, who owned Coronata Vineyard on the other side of Plegmund's Bridge. This rivalry came to a head when Count Vladimir Crespi, owner of the large and successful Belgaard Vineyard in southern Toussaint, was killed by The Beast of Beauclair, leaving his estate up for grabs.
If Geralt helps her after helping Liam get Belgaard: she'll be sad knowing she'll have to stick with being a small time wine supplier, but at least she won't go bankrupt now that her problems are fixed.
If Geralt helps her take over Belgaard: she'll gladly become steward of the vineyard and most likely becomes a huge supplier of wine.
If Geralt helps both but doesn't investigate the saboteur before the second part of Wine Wars: Belgaard: the two will grudgingly enter a partnership to run Belgaard together, but show resentment towards each other.
If Geralt ends Liam and Matilda's feuding: the two will happily enter a partnership, combining all three vineyards and, realizing they were attracted to each other, a relationship soon sprung up between them.