I'm Sorry about your mom. What type of stroke did she have? It sounds like the stroke occurred on the left side of the brain. The left side of the brain controls speech.
How soon her speech returns, depends on the severity of the stroke. Some folks regain their speech quickly. My mom had a severe ischemic stroke 2 1/2 months ago and she's just mumbling incoherent sentences. You should ask your mom's neurologist this question, and see if the neurologist can refer your mom to a speech therapist. I hope this helps.