The first printing of the 1852 LDS edition omitted the and here before the word thus. The second printing restored the and, the reading of both manuscripts and the early editions, including the 1840 edition (the probable source for the 1852 correction). Either reading is theoretically possible; the critical text will maintain the earliest reading with the and. For another example where and thus was reduced to thus, see under Alma 28:5 (in that case, it was the 1840 edition that omitted the and).
Summary: Maintain the connective and thus that begins Helaman 1:32, the reading of both manuscripts and the early editions.