Hey, your assumptions are almost right. It says:
#20."Maria Magdal.[ena] Nißler, gb. hier 1 Sept. 1790; hies.[elbst] unverheirath.[et], Bürgerstochter, evang.[elisch]; + Johannes Nißler, Bauer u. Rathsherr, + Maria Magdalena, gb. Klotz; 64 Jahre, 5 Mon.[ate], 17 Tage; Schleimfieber; hier d. 17. Febr. Abends 6 Uhr; hier 20. Febr. Nachmittags 1 Uhr."
Translation: Maria Magdalena Nißler, born here on September 1st 1790; living here, never married, daughter of a citizen, of evangelical confession; parents: the late Johannes Nißler, farmer and councilman here, and his late wife Maria Magdalena, née Klotz; she was 64 years, 5 month, 17 days old, died of slimy feaver, here on February 17th, at 6 p.m., and was buried here on Feb. 20th at 1 p.m.