Husbands converted from the spot on 66 minutes after Marc Williams was harshly adjudged to have handled the ball.
Wrexham dominated for long spells and Macclesfield were twice helped by the woodwork to keep the home side out.
The home side had Chris Llewellyn sent off on 70 minutes for two yellow cards, and Michael Proctor was given a straight red late on for a stamp.
Wrexham have now lost five consecutive games and boss Brain Carey's misery was compounded full-backs Ryan Valentine, Michael Williams and Eifion Williams picked up injuries.
Wrexham: Anthony Williams, Valentine (Marc Williams 43), Evans, Hope, Mike Williams (Pejic 37), Carvill, Spann, Crowell, Done, Eifion Williams (Proctor 59), Llewellyn.
Subs Not Used: Michael Jones, Johnson.
Sent Off: Llewellyn (71), Proctor (90).
Booked: Crowell, Spann, Llewellyn.
Macclesfield: Brain, Regan, Morley, McNulty, Jennings (Flynn 90), Wiles, Levi Reid, Hadfield, Thomas (Izak Reid 64), Gritton (Evans 57), Husbands.
Subs Not Used: Millar, Lowe.
Booked: Jennings, Husbands, Regan.
Goals: Husbands 67 pen.
Att: 1,503
Ref: Darren Drysdale (Lincolnshire).
BBC