RF Module gets stuck with DC Motors
To reduce EMI Problems I recommend:


place 100nF X7R Ceramic capacitors directly at U1 pin 18 and IC2 pin 16. 
add some µF X7R ceramic capacitor at IC1 pin 1 and 3. (2,2µF up to
10µF)
C1 is not intended to be "used" by IC1. It shall store the    energy
required by the Motor. Move C1 close to IC2 Pin 8.
Add some µF ceramic capacitor to IC2 Pin 8.
Add some nF ceramic capacitors between: 1y-2y, 4y-3y, 1y-GND, 2y-GND,
3y-GND and 4y-GND to filter the brush noise. The values need to be
tried.
choose ceramic capacitors which have Umax dubble the voltage of your
Max voltage.
Layout: use one solid ground layer without a single trace. other
Layers: Separate the traces with switching noise from the antenna &amp;
connector part


by this the EMI is not spreaded that much by the Motor and IC2 and the EMI imunity of U1 is improved