Is it permissible for me to visit my grandparents who spend the summer in a Christian village in Lebanon, given that I live abroad? Further, can I sit at a table where I am not free-mixing, but others are? For example, my grandmother and her sister sitting with their husbands.

Ustadh AbdulAziz al-Haqqan
Consider the fitnah may Allah reward u before doing anything and protect yourself from it.