The parish church
is All Saints. As it happens, Cawood parish church is also dedicated to All Saints, and their website (link in Reply #33) includes this comment:
Dedication to All Saints is frequently encountered in this area of Yorkshire: all three Churches in the Benefice, are dedicated to All Saints. This may be the result of a typically canny Yorkshire desire to hedge one’s bets, rather than trusting to the patronage of just one or two selected saints!
Where the Wistow church site mentions two churches, it will be referring to their partnership with Wistow Methodist Church; services are held in both, so you'll need to plan a trip for a day when there's a service in the parish church.
I noticed from the website that there isn't a vicar there at present, and services are being taken by (retired?) clergy from elsewhere. That probably means they won't know a lot about the church's memorials etc, so you might find out more from one of the lay people listed - who might even be prepared to meet you and open up the church on a weekday.