using the preterite + hace

Question

Ella se mudó allí hace dos meses.   Is this correct?  The lesson says we can't use the preterite with hace + time.

Answer

Hola Elvira,
this sentence is correct:
"Ella se mudó allí hace dos meses." 
What we are saying at the end of the lesson is that you cannot use the Perfect tense (not the simple past tense = sometimes called the Preterite) with "hace ..... que ....", which is a different structure. So, for this same sentence you would say:

Ella se mudó hace dos meses. (correct)
She moved there 2 months ago.

Hace dos meses que ella se vive allí. (correct)
She has lived there for 2 months.

Hace dos meses que ella se mudó allí. (correct)
She moved there 2 months ago.

BUT
Hace dos meses que ella se ha mudado allí. (incorrect)
There is a lesson explaining the use of "hace + length of time" (without que)
Have a look here.
Saludos
Inma