Is one ghusl sufficient if performed with the intention of embracing Islam, and for janabah and menstruation, or must there be a separate ghusl for each?

One ablution (ghusl (definition)) is sufficient if there are multiple reasons necessitating it, provided the person performing it intends to purify themselves from all of them. This is the opinion of the majority of scholars, as the states of impurity (ahdath) overlap, and if one intends to remove some of them, all of them are removed. Some scholars have considered apostasy (ridda) to be a state of impurity. Therefore, your performing one ablution for all states of impurity is sufficient. Those who hold the view that a disbeliever (whether an apostate or an original disbeliever) must perform ghusl believe that the ghusl performed upon embracing Islam suffices for all states of impurity that occurred while in a state of disbelief.