March 15 (Reuters) - Wall Street’s main indexes were subdued on Monday after logging their best week in six, as investors geared up for the Federal Reserve’s meeting this week amid caution over rising borrowing costs spurred by massive fiscal stimulus. The Dow Jones Industrial Average rose 20.2 points, or 0.06%, at the open to 32798.84. The S&P 500 fell 0.4 points, or 0.01%, at the open to 3942.96, while the Nasdaq Composite rose 3.6 points, or 0.03%, to 13323.472 at the opening bell. (Reporting by Medha Singh in Bengaluru; Editing by Maju Samuel)