Can hairs be taken from the front neck area for a beard transplant ?

Any hair follicle removed by any method (including FUE) will not grow back from the place it was harvested.  It will also leave a scar.  FUE harvesting will leave tiny round dot scars.  If you harvest from the neck area you may see these dot scars.  Finally the hairs around the neck may not be "permanent" hairs.

To answer your question, yes you can extract hair from the neck are. Some clinics discourage using neck hair because it isn't permanent however if you are informed of this, then you can use these hairs.

If you choose the FUE technique for beard transplant, you are always better off borrowing hairs from the "safe zone" in the back of the scalp than anywhere else on the body.  These hairs are the least likely be lost to genetic or hormonal factors over time. FUE scars will be visible as small white dots if you take hairs from the front of the neck.  Neither the front nor the back of the neck provides the most durable hairs for transplantation.  With time, they may be susceptible to loss more so than the ones on the back of the scalp.  Also, even if you like to  cut your hair short, the back of the scalp tends to have the best density to cover the scars of FUE. Despite some advertising claimes, FUE is not a scarless procedure.

It is not good medicine to use neck hairs as a donor source because these hairs are often not be permanent hairs. As a man ages, neck hairs change. For this reason, scalp hair is a better choice. 

There is an area in the back of the head that is resistant to DHT hormone.  This area contains the hairs that are permanent and usually last a life time.  If the hair is harvested from outside of that area, there is a chance that the transplanted hair may fall off in the future. 

Yes,  follicular units can be harvested from the frontal neck and under chin area.  The problem is the number of follicular units is too low for larger beard areas, but can work for smaller beard recipient areas.