Only three months into its first session, the 98th Congress has chalked up big accomplishments, Monitor correspondent Julia Malone reports. As they prepared to take a week-long Easter break, the lawmakers dotted the last ''i'' on the $4.6 billion jobs- and recession-relief bill. The measure now goes to the President for his signature. As of this writing, a major social security-reform bill appeared certain to win final approval as well. It is said to be the most politically sensitive and important legislation in the early months of the new Congress. House and Senate conferees agreed to drop a Senate provision that would have delayed inclusion of federal workers in the system.