My questions is can they do that since she is still living there and I thought they don't show the apt right before or after the tenants move.
Landlords have the right to show the unit during the notice period, as long as they provide written notice of at least 24 hours.

Also I thought the tenants have the right to know why they are getting evicted?
It sounds like your Aunt has been living on a month to month agreement. The landlord need not have a reason to terminate the tenancy, so long as s/he serves proper notice.