Assalamu Alaikum Warahmatullahi Wabarakatuh

Paternal Aunty's husband is not a Mahram, hence not permissible to travel with. You must have at least one Mahram or husband, to be able to travel over 48 miles.

It will be useful to clarify mahram here - i.e. A male
relative whith whom Nikah is never valid.

A paternal aunty's husband is not from this category
as nikah is permissible with him following the aunty's
death.

Wallahu A'alam