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.
It's either 3 years or 5 years, depending on when the transfers were made. The Medicaid look-back rules have to do with whether giving away assets, or transferring them for less than full value, will disqualify your mother from Medicaid coverage of her nursing home costs. Here the rules.