VirtueMart Price export does not support export of product category field. Product category field is supported in VirtueMart Product export and i also see the fields in your export template are all supported in VirtueMart Product export. May i ask why you are using VirtueMart Price export instead of VirtueMart Product export?
VirtueMart in its 3.8 version has added new fields to its database tables and the error is because of these new fields. Please load both of the patch files attached with the post here. The patch files are for VirtueMart product and VirtueMart category exports and will solve the error on export.