E.F. Hutton Group and Morgan Stanley Group, two of the nation's largest brokerage companies, reported healthy increases in first-quarter profits on the strength of the rising stock market. Hutton, based in New York, said net income for the three months ended March 31 rose to $66.1 million, up 26% from a year ago, while revenue rose 19% to a record $871 million. The results included an extraordinary credit of $26.8 million for tax benefits in 1987 and a credit of $5.2 million last year. Morgan Stanley, also of New York, said its net income rose about 11% to $64.27 million. Revenue totaled $747.04 million, up 26% from the same quarter of 1986.