Linda, my last message of this thread, of November 16, 2012, dated about 10:30 AM, provides ideas on how to advance your search. Have you worked with LDS microfilms? If you get stuck following our advice, please ask. I'd be happy to tell you how to go about ordering the right microfilms, but you need to give this matter the time and effort it needs.
The Kollerschlag films are based on the duplicate records, but - compared to the matricula records - they have the advantage of covering all years between 1819 and 1946. You will likely find the birth record of Rudolf (in the 1860s), and of his siblings, the birth record of Anna, the birth record of Josef in the 1920s (if there is such a record) and how he fits into the Christl tree, and the death record of Rudolf (in 1940). If Rudolf married in Kollerschlag, there will also be his marriage record. Among all these data, there will be the maidenname of Anna's mother.
The alternative to looking at the films at an LDS Library near you would be for you to wait for the digitized duplicates coming on-line. The target date was the end of 2012.
Other options for you are writing to the State Archive of Upper Austria, the Diocesan Archive and/or the parish of Kollerschlag. You could also contact the few Christls (Christels, Kristls and Gristls) who live in the Wegscheid and Kollerschlag region and have listed phone numbers.