Hello and thanks for the query
is quite common at this age (depends on person to person) due to cerebral atrophy
so not to worry about it. Cerebral atrophy is a process of loss of tissue and loss of cells resulting in loss of memory. But if you think she has delusions than you should consult your psychiatrist
and take advise from him. If she has no problem like fear from someone, talking alone etc than this should be normal but can create problem in future.
So in my opinion consult your doctor and follow the advises.