Automatic draw rules In developing a computer chess program, would it be reasonable to automatically declare a draw match for these two scenarios:

A.  Player 1 has a king and a knight, player 2 has only a king left.

B.  Player 1 has a king and a bishop, player 2 has only a king left.
Yes, since it is not possible to produce a checkmate in these circumstances.
See also the FIDE rules:

1.3 If the position is such that neither player can possibly checkmate the opponent’s king, the game is drawn (see Article 5.2 b).
5.2 b The game is drawn when a position has arisen in which neither player can checkmate the opponent’s king with any series of legal moves. The game is said to end in a ‘dead position’. This immediately ends the game, provided that the move producing the position was in accordance with Article 3 and Articles 4.2 – 4.7.