A 250 watt hub is minimal assistance for a lightweight two wheeler. That trike is heavy. Slight boost would be noticed on level ground but there wouldn't be much energy on inclines and zip on hills, especially with a load of stuff in the basket.
If you need a trike, get one and put a stronger mid-drive kit on it.
https://tinyurl.com/yd2bjn9q
The forum host has info on the drives
https://electricbikereview.com/?s=8fun+mid+drive