However, it should be noted that modern customs may have changed. In some places, digging graves may be regarded as an unlucky activity, even if it is helpful. This may depend on local culture, religious beliefs and personal ideas.
In addition, if your friend's family has special customs or beliefs, such as funeral ceremonies of some ethnic minorities or religions, you may need to understand and respect their customs.
The best way is to communicate with the host family before offering help, understand their customs and culture, and make sure that your behavior will not offend them. If they need help and you are willing and able to help them, then you can help them. If they don't need your help or have special customs to follow, then you should respect their decision.