If your mother is a US immigrant, she can buy a house using her own credit.
If she is a Foreign investor, she can buy with a larger down payment without using your credit. If she does not have a larger down payment, she can still buy using your credit. You would need to co sign and be on Title.
Help-U-Sell Achievers Realty
40083 Mission Blvd
Fremont, Ca. 94539
Although you mentioned that your mother is not a citizen or resident alien, you did not mention what type of Visa she may be holding. H-1 Visa holders can buy homes fairly easy, especially in conforming territory (loans under $417k). FHA works the same. If she is a foreign national, however, she is looking at a minimum of 30% down (most will look to 50% down currently). Don't forget, she must qualify with her income as well to be able to afford the home, so a job (as well as credit) are pretty important when buying under either scenario. As a resident, you are able to purchase a home just as any citizen would - which means that all loan programs are available to you.
Thank you for your question.
As a foreign national anyone can purchase property in the US. It is possible for her to arrange for financing but lenders that are doing these loans are requiring a 30-40 % deposit.
Another option, as you mention, is making the purchase yourself on behalf of your mother.