A quart is 2 pints. A pint is sixteen fluid ounces of water and weighs about 16 ounces (avoirdupois weight.) A gallon is 4 quarts (8 pints) and thus weighs about 8 pounds. Five gallons would be about 40 pounds.
In some cases, if your mother is on Medicaid, she can designate you as her personal home care aide and you can get paid a small amount through Medicaid. If your mother has her own resources, you can draw up a contract agreeing to work as her home health aide and she can pay you a salary that you both agree upon.
Many parents will do almost anything to help their kids, including giving them money when they're in a bind. If you have a good reason for asking and your parents can afford it, asking politely and presenting a plan to pay them back will probably win them over.